Disclaimer - I do not own Harry Potter
A Different Professor
Chapter One – Which Professor?
Gryffindor Common Room
"You want to what?" asked Harry, staring at his friend with wide eyes.
Ron's devastated expression did not change with Harry's question; he just continued to stare at his hands worried about his sister. "We should tell Lockhart what we know; he might be able to use it to save Ginny."
Harry shook his head in disbelief, "Let me get this straight, you want to go tell Lockhart that we think the entrance to the Chamber is in the girl's bathroom on the second floor and that a Basilisk petrifying everyone."
Ron looked up and blinked, "Well, yeah," he said simply.
"You heard him Harry, he suspects something and he said he was going after my sister. This information could help him save her."
"Ron stop being a git," said Harry with a sigh.
A look of horror took over Ron's face. "Don't you want to save my sister?" His voice had risen in volume and people around the common room were starting to notice them. "He said he was going to save her so we should help him if we can. She is my sister and if you were my friend you would do this for me." Ron was shouting as he finished. He glared at Harry, his face now blending in perfectly with his hair.
The entire common room was looking at the two friends, shock and pity on their faces. Gryffindors stuck together and right now the two second years were not acting like Gryffindors, especially not ones who were best friends.
"That is not what I meant, Ron," Harry's voice was barely a whisper. He sighed, "You know I want to save Ginny I just don't think that Lockhart is the answer."
Ron gapped at him, "But he's done all that stuff he wrote about in…"
"Ron, I seriously doubt that a man who can't handle a dozen Cornish Pixies can handle a hag let alone a Yeti or a Werewolf. He banished the bones in my arm instead of healing them and Snape made him look like a first year who had never cast a spell in that dueling club. Lockhart is a media hungry ponce, not the hero your sister needs."
The taller boy was silent for a moment but then his eye turned hard and anger seemed to radiate off him. "I know what this is about, Potter," at the pronouncement of Harry's last name spittle flew from his mouth and he moved in a manner resembling an angry Malfoy, but with less pure-blood arrogance. "You just want all the glory for yourself. You are going to turn the wizarding world away from everyone with more fame then you, Lockhart is just your first conquest." He turned and stalked to the portrait, "I don't care what you do but I am going to go to Lockhart and help him save my sister."
Harry just closed his eyes as the portrait slammed behind his friend. It was hard enough to keep his own fear for the youngest Weasley in check, he really didn't have enough control to keep Ron's explosive anger at bay. Harry really missed Hermione.
He opened his eyes when he felt two nearly identical arms fall over his shoulders. He was surprised to see Fred and George, until a moment ago they had been huddled in a corner completely isolated from everyone else, terrified for their sister.
"Don't worry about him," Fred began.
"Harry, he," George continued.
"Just can't handle,"
"The pressure, so he is,"
"Taking it out on you," They said together.
Fred stepped around so he was in front of Harry instead of at his side. His eyes were a mere shadow of their former self; they just didn't have the spark and humor they usually held. "I mean Hermione won't be un-petrified for a few more days so who else is he going to yell at when he is confused?"
"Yeah, Harry," George added, "He is afraid of us and he doesn't talk to anyone else so that leaves you."
"Thanks for that, guys," Harry said with a small smile, it didn't reach his eyes but it was still a smile.
"No problem, Harry," said George.
"Now, for the reason we came over here," Fred said, a bit of mischief making its way into his eyes.
"Was what little Ronnie said true?"
"Do you know where the Chamber is?"
"Do you know what the monster is?" they finisher in unison again.
Harry looked at them then shrugged, "Yeah, I think we figured it out." He paused then reached into his trouser pocket, "Hermione had this in her hand and everything kind of fell into place."
He passed the scrap of paper to Fred, and the twin redheads focused on the words both printed and written on the yellowed paper. As one, their heads snapped up and looked at Harry, then at each other.
"It makes sense," said George.
Fred nodded, "But how are they not…"
"The water," said George.
"And wasn't Penny holding…"
"A mirror," George finished.
"Why the girls' bathroom on the second floor?" asked Fred.
Harry looked from one twin to the other then took a deep breath. "The last time the chamber was opened there was one death, and she hasn't left the school. Perhaps she is still in the room she died in; the second-floor girl's toilet. At least that is what I think happened."
He saw recognition flash in their eyes and then they looked at each other. They nodded and then each grabbed one of Harry's elbows and walked toward the portrait hole. "Well," Fred said a bit louder than necessary, "I guess we should go find little Ronnie, this is a time for family."
"Yes, Dearest Fred, we can't allow our baby brother to suffer alone. We must go after him, as we are his wonderful older brothers."
Once out in the hall they pulled Harry into a small alcove and George pulled out an old ragged sheet of parchment. "This Harry is the secret to our successes here at Hogwarts and tonight it is going to help us save Ginny."
"I solemnly swear I am up to no good," the redheads said in unison as Fred touched his wand to the parchment.
Harry's eyes widened as writing appeared proclaiming that this was the Marauder's Map and then proceeded to make a complete map of Hogwarts, with moving dots indicating each person in the castle included. He would have to ask them about it later, when the situation wasn't so dire.
"Alright," said Fred. "Now to find Lockhart and see if he is actually going to help."
The three searched and found Ron immediately, he was in Lockhart's office and he wasn't moving. They frowned at each other and continued their search. It was George who gave a gasp of triumph. "The ponce is heading out the front doors with surprising speed; I don't expect he will be coming back."
"Now that the useless git is out of the way, who should we go to for help?"
"We are not capable of taking on a Basilisk, even if you took on a mountain troll in first year, a basilisk is a whole other level of danger even if you speak Parseltongue."
Harry was looking at the map and had a sudden idea. "I think we should go to McGonagall's office; she's there with Snape." He paused and then elaborated when he saw the surprise on the twin's faces, "I may not like the man but he seems to know what he is doing and honestly anyone who can knock Lockhart on his butt and make it look like he was merely teaching deserves a chance."
The twins nodded, unlike every non-Slytherin student, they liked Snape. He may be the unfair dungeon bat but he taught potions and a good portion of their 'work' involved potions so they were determined to learn all they could from the man, though they still had to make his life miserable, they had a reputation uphold after all.
Transfiguration Professor's Office
Minerva McGonagall paced her office with the ferocity of a lioness on the hunt; so utterly intimidating that one would wonder why her animagus was a tabby as opposed to the queen of all cats. Though she was a terrifying sight to behold she was in fact at a loss for what to do. One of her cubs was in danger and she feared she would never see her again.
Severus Snape, however, sat stiffly in one of the visitor's chairs in her office. He had not, as he usually did, transfigure the cushion from red to green; he too was worried for his student even though she was a reckless Gryffindor.
The heads of house had agreed that with Dumbledore removed from his post by the school governors that Pomona would send word to the DMLE and Filius would be in charge of the students while Severus and Minerva tried to figure out the mystery that had been stumping wizards for hundreds of years.
At a knock on the door Minerva paused her pacing, Severus turned his head to the door. Without waiting for a reply the door burst open and three young Gryffindors tumbled in, barely managing to remain upright.
"Mr. Potter, Misters Weasley you should be in your dorms not roaming the castle," their head of house said in utter exasperation. She wasn't all that surprised that the students roaming the castle were these three, they were often where they shouldn't, it was however surprising that the youngest male Weasley was not with them.
"I know professor, and I'm sorry but there is something I think you should know." Harry's demeanor was serious as he stared at his sternest professors.
"Yeah, Professor," said Fred, "Harry might have figured out the mystery of the Chamber of Secrets." Normally the twins would have split the statement but they had a sort of understanding with Snape on that count; they didn't split their sentences and he let them ask questions on the art of potions, as long as no one else was around of course.
"Is this true, Mister Potter," McGonagall was trying not to put too much stock in the statement.
Snape looked to the small second year and raised an eyebrow, "Enlighten us, Potter."
Harry looked at his professors and then the twins. At the encouraging nods, Harry took a deep breath and reached into his pocket pulling out a scrap of parchment. He handed the parchment to Professor Snape, as he was closer, "I think Slytherin's beast is a Basilisk and that the entrance to the chamber is in the girl's toilet on the second floor."
Snape studied the scrap and then handed it to his colleague, not showing any change in his expression. The older professor took a moment to study the information presented to her and looked at Severus, "Hagrid's roosters," was all she said.
Snape grunted in agreement, "There has also been a noticeable lack of spiders, even in the dungeons."
"How is it that not one student has been killed?" McGonagall asked.
"Because they didn't look directly into the eyes of the Basilisk," George said quietly.
"The Creevey boy was holding a camera, was he not, Minerva?"
"Yes he was, Severus. Miss Granger and Miss Clearwater were found with a mirror."
"Justin was found with Nearly Headless Nick," George added.
"A ghost can't die so he took the killing glance while Justin saw it through him," finished Fred.
"And that blasted cat?" asked the dark professor.
"The girl's toilet had flooded," Harry said knowing his professors would draw the same conclusion he had.
"This is impressive work, Potter," said the tall man, "I find myself impressed by the sound deductions you have presented."
Harry shook his head, "It wasn't me sir, Hermione figured it out. She had that in her hand, I found it this afternoon when Ron and I went to visit her."
Snape nodded, that did make more sense, the girl was very bright. "Why do you think that the entrance is in that particular location?"
"Moaning Myrtle," Harry answered simply but continued when his professors gave him skeptical looks. "Well I heard that a student died last time the chamber was said to be open and then I remembered the young ghost girl who was always crying and flooding that bathroom. What if the student who died never left? And even if it isn't there then maybe she could give us an idea of where it really is."
The students stood in silence as the two professors seemed to have a silent conversation. Snape gave an almost imperceptible nod and turned to the boys while McGonagall said something under her breath, a silver tabby appeared on her desk. She spoke to the cat and then it flew out of the office.
"Now normally I would demand that the three of you return to your common rooms but I feel there may be some need for young mister Potter in this." He smirked at the look of shock on the Gryffindor faces. "As this is Salazar's hidden chamber it would infer that the entrance would be guarded in a way that only he and his descendants could bypass." He smirked at the young man, "Parseltongue, Mister Potter, I believe that any password would be set in Parseltongue and as you are the only living individual who speaks it that I am in acquaintance with I fear that I will have to take you with me."
He turned his attention to the twin terrors behind the second year. "I am going to allow you to accompany us on the assumption that if I forbad you to join us you would find a way to follow despite anything I said or did." He smirked at the somewhat guilty nod the twins gave him. "Your job will be to ensure young Mister Potter doesn't get himself into any more trouble, as he seems hell bent on spending his time in the hospital wing."
Harry frowned while the twins nodded again, determination in their mischievous eyes.
"How are we going to destroy the monster, Severus?" asked McGonagall. "If it is in fact the same monster as the one he placed while still in the school it would be enormous. I do not know how we could fight something of that size while still avoiding its gaze and fangs."
"If only we had a rooster," was his bland reply.
Minerva frowned then shouted, "Mipsy."
A small gray creature popped into the room. Harry recognized it as a house elf, though this one was obviously female and was much less nervous than his strange friend Dobby.
"Mipsy be at your service, Professor," said the squeaky creature.
"Mipsy, I need you to get me a rooster as fast as you can and bring it to the girl's toilet on the second floor. We are heading there now and we will need it if we hope to save the young girl that has gone missing."
The house elf popped out of the room without a second thought. "Shall we gentlemen," she said indicating the door. "I have given Filius and Pomona a brief summary of what we are doing and they will inform the other teachers of our plans."
At this the twins spoke up, "You might want to tell them that Lockhart is a lost cause."
"He walked out the front door and left Ron unconscious in his office," Fred finished.
"We went after Ron; he left to go tell Lockhart what we knew. We had decided to come to you because you have been teachers longer and we…"
"Stop trying to be nice, Harry," said Fred.
"Yeah," George continued, "I am sure the professors know that Lockhart it a worthless, cowardly ponce."
McGonagall gave the twins a stern look while Snape smirked.
"We did not expect help from Lockhart so there is no need to worry, Mister Potter. Either Professor Flitwick or Professor Sprout will retrieve the youngest Weasley and take him to the hospital wing."
They finished their journey to the second floor in silence.
Hogwarts Second Floor
The group approached the restroom at a fast walk. They avoided the message on the wall announcing the fate of the youngest Weasley. Professor Snape slowly opened the door to the girl's bathroom looking for signs of movement. Deciding it was clear he stepped into the slightly flooded bathroom and indicated for the others to follow.
There was a cry and suddenly they were faced with the incorporeal form of Moaning Myrtle.
"Oh, it's you," she said looking at Harry, "What do you want?"
Harry shank away from his professor's raised eyebrow but answered the young ghost. "I wanted to know how you died."
"Oh, it was horrible," she seemed happy to tell her tale. "I was crying because Olive Hornby was making fun of me when I heard a male voice. I came out of the stall to tell him to go away when I saw a pair of great big yellow eyes over there and then I died." ***
"Thank you for sharing that with me, Myrtle," Harry said respectfully to the distraught ghost.
Together Harry, the twins and professor Snape walked toward the sink Myrtle had indicated. Before they could do anything, the little house elf reappeared this time with a very unhappy rooster. "Mipsy brings the loud chicken, Professor. I's borrowed him from the grumpy man with the goat the sparkly Headmaster sometimes visits."
A small smile played at McGonagall's face at the house elf's description of the Headmaster and his brother. "Thank you, Mipsy, you have done well." She slashed her wand to the irate rooster and silenced its irritated squawking. "I'll be silencing him until he is needed. If you would, Mister Potter, I believe you will have to do the honors."
Harry nodded and walked closer to the sink. "Open," he said but realized that he had spoken in English and not the language of snakes. He looked closer at the sink and saw there was a carving that looked serpentine along the faucet. He squinted at the carving and once again said, "Open."
At the hissed word the floor began to move. As they watched, a hole was opened in the floor and a slope leading down toward the lowest portions of the castle was revealed.
"Well done, Mister Potter," said McGonagall.
Harry made a move to enter the tube but Snape placed a hand on his shoulder stalling him. "I would think that a man of Salazar Slytherin's talents would have had another way of entering his sanctuary." At his student's blank look, he said, "Stairs, Potter, I am sure he was capable of transforming this pipe into stairs with only a word. Sliding down a slimy pipe would have been beneath such a man."
"Oh," Harry said a little embarrassed. "Right," he sucked in a breath and hissed, "stairs." As the potions professor had guessed, the tube did in fact become stairs with just a single word in Parseltongue.
Snape nodded to Harry, the closest thing to a complement he was going to get, and started down the steep stairway, leading the way. George clapped Harry on the shoulder and followed the potions professor.
"I'm right behind you Harry," said Fred as he pushed the younger boy ahead of him. He then turned and nodded to McGonagall, he and George would protect the boy who might have just saved their baby sister. McGonagall took up the rear levitating the rooster in front of her.
The somewhat slippery stairwell led to a cave like room littered with the bones of animals and an enormous snake skin. Severus crouched next the skin studying it, a look of surprise on his face. "This basilisk has to be at least fifty feet long by now if not seventy." He looked to Minerva, "This could be very dangerous, have that rooster ready to start crowing."
They turned to the far side of the chamber to see a large circular door blocking their way. It was decorated with snakes so Harry stepped forward and once again used his Parseltongue abilities to open the newest door.
The group stepped into a long chamber lined with stone snakes, at the end, near a giant sculpture of a human head, lay Ginny Weasley. The young Gryffindors, typically, forgot all caution and ran to the prone girl. Severus and Minerva, however, remained near the entrance, attempting to keep their presence unknown for the time being. They wanted to know who the young man standing over the small girl was. He wore Slytherin robes but neither Severus nor Minerva had ever seen him.
"Ginny," the three boys said at once, fear apparent in their voices.
"She won't wake," said the older teen.
When Harry asked 'Tom' what was wrong with her the others were surprised. How did Harry know this boy's name when the teachers and twins did not? Severus and Minerva were shocked when the boy described Ginny's relationship with the diary and what it had done to her. It shocked them that such a sweet girl had been forced to do those things completely against her will.
Most surprising however was when he wrote his name in flame and the letters rearranged themselves to read 'I am Lord Voldemort.' The young man then spoke in Parseltongue and mouth of the stone face began to open slowly.
It was then that Severus turned to Minerva. She nodded at him, the second they saw movement the rooster would be crowing. Severus cast a disillusionment spell on them and they made their way forward as quietly as they could. When the shadows near the opening started to shift, Minerva removed the silencing spell on the rooster and agitated it so it would begin crowing. Severus amplified the sounds with a sonorous, just to ensure that the crowing reached the gigantic serpent.
The rooster crowed and crowed and the wizards covered their ears to block the reverberating calls. Severus watched the mouth of the statue, hoping their plan worked but fear fell upon him when he saw the great snake's massive snout. He instantly turned, facing away from the snake, and stepped in front of his colleague.
"It didn't work." He hissed hoping he was blocking her view of the snake's deadly gaze. "Remind me to kill the author of that book if we survive this."
"Severus, I am sure the author is long dead."
"Then I will resurrect him for the sole purpose of killing him."
She sighed, "I do not believe this is the time for this discussion. We need to find a way to kill the beast while avoiding its gaze and keeping my lions safe at the same time." Minerva paused for a moment, "Perhaps the reference to the rooster was not for its call but for what the call typically signifies. Perhaps the Basilisk can't see by the light of the sun and thus is never seen around roosters because they announce the rising of the sun."
"It is worth a shot," the dark man said after a short pause.
As one they turned, eyes to the ground, from the corner of his eye, Severus noted that the Weasley twins had dragged both their sister and Potter to one of the snake statues along the wall and they were huddled behind it, all three boys looking way from the snake.
"SOLARIS MAXIMA," the professors bellowed as one, shutting their eyes as they did.
The giant snaked roared in pain as light as bright as the sun flooded the subterranean cavern.
Again, the professors aimed their wands as one and sent blasting hexes to the temporarily blinded snake's eyes. Severus smirked as his hex hit the snakes left eye bursting the deadly organ into a mass of blood and tissues. Hearing Minerva curse next to him he noticed her spell had not hit its target, it had hit the nearly invulnerable scales surrounding the eye of the snake.
They fired blasting curses again, both aiming for the undamaged eye. They fired another two curses each before the second eye was destroyed, it was nearly impossible to hit the eye of a thrashing animal so far above their heads.
Severus turned to the side and saw that Fred, at least he thought it was Fred, had his wand pointed at the young Voldemort, whose hand was now empty. The young Slytherin growled at the red head and started toward the wand that had flown from his hand.
Riddle would not regain the wand though because he was no match for the youngest Gryffindor's speed, Harry sprinted from his hiding place, slid on the wet stone and took the wand into his empty hand. The Gryffindor stood and pointed two wands at the snarling teen while backing away. Twin red heads stepped to their young friend's side, one taking back his wand back, and Riddle now had three wands pointed at him.
"No matter," Riddle said, "my dearest may not be able to kill you with a glance but she can still swallow you. I guess I will just have to listen to your screams as she sinks her teeth into you."
"Weasleys, Potter," Severus called, "back away from him and get back to Miss Weasley." He looked to Minerva, "We will have to do this the hard way."
"How will we kill it Severus, a Basilisk's skin is even more resistant than dragon hide?"
"A Basilisk's skin may be spell resistant but its soft tissue is not."
"What do you mean Severus?"
"If I can hit her with a blasting hex or cutting curse in the mouth I believe I can kill her."
The older woman stared at the man in shock. She blinked, "You can't be serious Severus, the chance of you surviving such an idiotic plan is nearly impossible. If you miss, you will be in her mouth and therefore dead. If you do cut her open from the inside it is highly likely she will fall on you, which is just as likely to kill you due to her size and in the off chance you don't get crushed you could very well be hit by her fangs; basilisk venom is perhaps the most poisonous substance in the world."
"We have no choice Minerva; I am faster and stronger and thus have a better chance of surviving this than you do."
"Very well but if you die, I will kill you myself."
"Of course, Minerva," he stepped toward the now calmer snake, "oh and could you do something about the angry young Slytherin over there, I find him to be quite irritating. Do not be fooled by the fact that he does not appear to be carrying a wand. I suspect he took George's wand so that there were less wands to point in his direction, it is highly likely he has stashed Miss Weasley's wand somewhere and is waiting to reveal it at the most opportune moment."
"With pleasure," she said with a smirk. Minerva turned toward the young man prepare to incapacitate him but then she noticed a wand in his hands, Severus was right. Her eyes flicked toward her three trouble making lions, each of the boys clutched their wand so it must be Miss Weasley's, and he did indeed have the wand before they entered the chamber. He cast a spell at her when he noticed her approach. Minerva dodged the spell with ease and readied her own wand, letting a retaliatory spell fly a moment later. She would not lose to a school aged Lord Voldemort.
Severus threw blasting and cutting curses at the giant snake hoping to irritate it into striking at him so he could finish it. The snake seemed to be more interested in the others but kept hissing at him after every curse connected with its skin, not in pain but in annoyance.
"Come on, you scaly bastard, strike at me," he growled. As he said this he cast a particularly powerful cutting curse and the curse hit the snake right in one of its damaged eyes causing the snake to scream in pain.
He smirked as the snake focused on him at last. The snake reared up then plunged down toward the dark man. Severus aimed his wand at the snakes wide open mouth. Putting all his reserves into the spell, he fired his final blasting hex straight down the snake's throat. His spell tore through the skin of the snake's mouth, blood exploded from the wound along with what looked like brain matter. His one and only chance appeared successful.
Severus scrambled back as the snake fell, its head landing less than a foot from his feet, the floor shacking with the impact. He attempted to wipe blood from his face but most of him was covered in the coppery substance. Severus turned his attention to the rest of the chamber; the young Dark Lord needed dealing with.
The young man screamed in anger, "What have you done," he shouted at the professors. "You have destroyed the queen of serpents." He snarled and looked toward the young students. A smile spread across his face, "I suppose I can live with this, for you are too late. The girl has only moments and then she will be dead, her life force will leave her and make me live once more."
Severus rushed toward the raven-haired boy and the diary. He cast a myriad of spells at the diary but with little effect. Frustrated, he slid a knife from a concealed sheath in his boot and with little ceremony or thought plunged the knife into the battered black book.
While he had been attempting to destroy the book, Minerva had been protecting her lions. Fred and George were crouched in front of Harry and their sister attempting to block the younger students if the duel between McGonagall and Tom got too out of hand.
Minerva was surprised. The boy was good for a student, but she was better. He may be the future Lord Voldemort but he was still just a sixteen-year-old so he hadn't yet learned all of Voldemort's most terrifying curses. She cast a shield between the boys and their duel and then focused on pushing back the young miscreant with the style and skill of a Transfiguration master.
The scream coming from behind the shield startled both duelers. It was then that Tom saw the knife plunged into his diary and the black blood like ink leaking out of the book as it screamed. "NO," he screamed as his body lost substance. He knew that he could not survive this, he had not yet gained a complete body as the girl was still alive, "I will return, Potter and I will kill you." With those final words the Slytherin teen faded from existence.
Minerva McGonagall smoothed her robes and picked up the wand the Riddle boy had dropped. "Hold on to that for your sister, Mister Weasley," she handed the wand to the nearest twin.
Harry and the other twin were kneeling next Ginny and the young girl was beginning to stir. She was afraid and beginning to ramble about what she had done while apologizing.
"Enough of that, Miss Weasley," Minerva said with authority, "we will speak of this all later but first we should return to the upper levels of the castle. Someone has some very distraught parents waiting up there," she said giving Ginny a pointed look.
The students stood and started toward the circular door they had entered from. Severus tucked the diary into a pocket and slid the knife back into its sheath. Standing, he looked toward the entrance to the basilisk's lair.
"You can come back later and harvest it for potions ingredients Severus; I am sure Mister Potter would let you in and split the profits of the carcass with you." She turned to follow her lions, "He may insist that Miss Granger and the Weasley children share in the profits but considering the size you believe the creature to be it should still be a sizable profit for everyone."
"It is mine by conquest."
She smiled, "True, but you would not have had the chance to defeat it without, Harry. Nor will you be able to harvest it without him."
Severus glanced on last time at the gigantic carcass, cast a preservation spell and then turned to follow his colleague. His student was safe, but the circumstances that put her in danger brought forth too many questions for comfort.
***(Paraphrased from Harry Potter and the Chamber of Secrets)
For those of you just starting, I hope you like the first chapter of my first ever story.
For all - this is self edited with some help from other authors along the way so if there are errors, I apologize.
6/4/18 - Just some editing and fixing. For some reason there is a section that likes to lose its formatting so if that happens again, for the 5th time, I am sorry (though it shouldn't I went through an fixed it three times this morning...
A note on Minerva not recognizing Tom in the Chamber: I have always wondered where people got the idea that they were in school together. It was never said in the books so I went searching. I am going off Wiki for this story, I know that isn't always accurate but this article said that it calculated back using her own words stating she started teaching in 1956 and an article that said she worked at the ministry for 2 years before teaching which would mean she attended school between 1947 and 1954. Tom Riddle opened the Chamber of Secrets in his fifth year, 1942-1943, which would mean he graduated in 1945, two years before Minerva started. So she would not necessarily even know his name because there would be 2 head boys between his leaving and her starting.