"Good morning, class. Are we sitting comfortably?" The Doctor asked the class as I sat at the back as his teaching assistant, jotting down notes. I had to wear the tightest black skirt ever, but apparently The TARDIS didn't have anything else appropriate for this situation which I think is utter bullshit, with a white shirt. "So. Physics." He said, scrawling 'physics' across the board before throwing the pen onto the table in front of him. "Physics. Eh? Physics. Phyyyyyyyysics. Physics! Physics. Physics, physics, physics, physics, physics, physics, physics." He sniffed at the bemused class of kids. "I hope one of you is getting all this down. Um, okay - let's see what you know. Two identical strips of nylon are charged with static electricity and hung from a string so they can swing freely. What would happen if they were brought near each other?" A boy put his hand up. "Yes - uh, what's your name?"

"Milo." The boy replied.

"Milo! Off you go."

"They'd repel each other because they have the same charge."

"Correctamundo! A word I have never used before and hopefully never will again. Question two - I coil up a thin piece of micro wire and place it in a glass of water. Then I turn on the electricity and measure to see if the water's temperature is affected. My question is this; how do I measure the electrical power going into the coil?" Milo's hand shot up again. "Someone else." Nobody responded. "Nope... ? Okay, Milo - go for it."

"Measure the current and PDs in an ampmeter and a voltmeter." Milo replied as I got up slowly and walked to the front of the desk next to The Doctor.

"Two to Milo! Right then, Milo, tell me this; true or false - the greater the dampening of the system, the quicker it loses energy to its surroundings."

"False."

"What is a non-coding DNA?"

"DNA that doesn't code for a protein."

"Sixty-five-thousand-nine-hundred- and-eighty-three times five?" I asked, thinking of the first numbers that popped into my head.

"Three-hundred-and-twenty-nine-thousand-nine-hundred-and-fifteen." The Doctor nodded at me.

"How do you travel faster than light?" The Doctor asked.

"By opening a quantum tunnel with an FTL factor of 36.7 recurring."

...

"These chips taste a bit funny." I mumbled to The Doctor as we sat in the canteen.

"Two days." We looked up and Rose was next to us, wiping the table. "Two days, we've been here."

"Blame your boyfriend, he's the one who put us onto this. And he was right. Boy in class this morning - got a knowledge way beyond planet Earth."

"You eating those chips?"

"Yeah, they're a bit... different." The Doctor remarked and I nodded.

"I think they're gorgeous. Wish I had school dinners like this."

"It's very well behaved, this place. I thought there'd be happy-slapping hoodies. Happy-slapping hoodies with ASBOs. Happy-slapping hoodies with ASBOs and ringtones. Yeah? Yeah? Oh, yeah! Don't tell me I don't fit in. What was your school like?" The Doctor asked me.

"Leadworth?" I frowned. "It's a very quiet little village, most people live well into their nineties. School same as any, just, less fuss was made. It was mainly me, Amy and Mels causing all the trouble and Rory following us around like a lost puppy."

"Aren't you quite the rebel." Rose muttered under her breath before another dinner lady approached us.

"You are not permitted to leave your station during a sitting." She said blandly to Rose.

"I was just talking to these teachers. They doesn't like the chips."

The dinner lady turned to us, "The menu has been specifically designed by the headmaster to improve concentration and performance. Now, get back to work." She turned and walked off, Rose following backwards, looking at us.

"See? This is me." She said, gesturing at her clothes. "The dinner lady."

"I'll have the crumble."

"I'm so gonna kill you." She muttered, turning and walking off but something caught The Doctor's eye, a teacher, talking to a student before he walked off and The Doctor looked back to me.

"How come," I began, dropping my fork onto the plate gently and pushing it away, leaning onto the table and looking at The Doctor. "Rose had to be a dinner lady, and I ended up your assistant?" I asked as we both got up, heading out of the canteen to the classroom.

"I've got to keep a eye on you."

"I'm not a dog!"

...

"But yesterday, I had a twelve-year-old girl give me the exact height of the Walls of Troy... in cubits." One of the teacher's told us as we stood in the staff room.

"Finch arrived three months ago. Next day, half the staff got flu. Finch replaced them with that lot." He nodded over at a group of teachers on the other side of the room. "Except for the teacher you replaced, and that was just plain weird, her winning the lottery like that."

"How's that weird?" The Doctor asked.

"She never played! Said the ticket was posted through her door at midnight."

"Hmm! The world is very strange."

"Excuse me, colleagues," We looked up at the door to see Mr Finch, the headmaster, standing at the door standing with a older woman with brown hair, who The Doctor froze at the sight of her. "- A moment of your time. May I introduce Miss Sarah Jane Smith." He nodded at the woman beside him. "Miss Smith is a journalist, who's writing a profile about me for the Sunday Times. I thought it might be useful for her to get 'a view from the trenches', so to speak. Don't spare my blushes." He nodded at everyone before walking away as Sarah Jane walked over to us.

"Hello!" She said brightly.

"Oh, I should think so!" The Doctor said, mesmirised.

"And, you are... ?" She asked but The Doctor stayed in shock.

"This is John Smith." I said, smiling softly at her.

"John Smith? I used to have a friend who sometimes went by that name."

"Well, it's a very common name!" I chuckled.

"He was a very uncommon man." She sighed. "Sorry, being rude, and you are?" She asked, holding out her hand to me.

"Flo, Flo Maxwell." I grinned at her and shook her hand.

"Nice to meet you!"

"Nice to meet you! Yes! Very nice! More than nice - brilliant!" The Doctor finally said before going back into shock.

"Um... so, um, have you worked here long?"

"No! Um, it's only our second day." I said, trying to distract Sarah Jane from The Doctor's odd expression.

"Oh, you're new, then? So, what do you think of the school? I mean, this new curriculum? So many children getting ill - doesn't that strike you as odd?"

"You don't sound like someone just doing a profile." I giggled.

"Well, no harm in a little investigation while I'm here."

"No. Good for you." The Doctor laughed as Sarah Jane walked off towards some other teachers. "Good for you. Oh, good for you, Sarah Jane Smith." He said proudly.

"Want to explain?" I asked, nudging him in the side before he turned round to me and told me all about his Sarah Jane Smith.

...

"The Doctor opened a fire door and me, him, Rose and Mickey walked silently through into the school.

"Oh, it's weird seeing school at night. It just feels wrong." Rose said. "When I was a kid, I used to think all the teachers slept in school."

"All right, team." The Doctor began before cringing, "Oh, I hate people who say 'team'. Um... 'gang'. Um... 'comrades'. Uh... anyway, Rose, go to the kitchen and get a sample of that oil. Mickey, the new staff are all Maths teachers, go and check out the Maths department. Me and Flo gonna look in Finch's office. Be back here in ten minutes." He said before grabbing my hand and pulling me off towards Finch's office.

...

After hearing some noises, we found ourselves inside the gym, watching as Sarah Jane backed out of a room and slammed the door. She turned around slowly and looked at The Doctor in horror as I stood slightly behind him as he clutched onto my arm behind him.

"Hello, Sarah Jane." The Doctor said softly.

"It's you. Oh... Doctor..." Sarah Jane whispered, smiling and walking forward. "Oh, my God, it's you, it's... it's... you've regenerated."

"Half a dozen times since we last met."

"You look... incredible."

"So do you."

"I got old."

"You're not old." I mumbled as The Doctor gently let go of me and let me walk round slowly next to him.

"What're you doing here?"

"Well... UFO sightings, school gets record results - I couldn't resist. What about you?"

"Same." They both laughed before Sarah Jane's laugh dropped. "I thought you'd died. I waited for you and you didn't come back, and I thought you must've died."

"I lived. Everyone else died."

"What do you mean?"

"Everyone died, Sarah."

"I can't believe it's you." She whispered before Mickey's screams filled the air. "Okay! Now I can!" The Doctor grabbed mine and Sarah Jane's hands before running out of the gym and towards the screaming, running into Rose.

"Did you hear that?" She asked, before noticing Sarah Jane. "Who's she?"

"Rose, Sarah Jane! Sarah Jane, Rose." Sarah Jane and Rose shook hands and I tried not to laugh as Sarah Jane smiled fakely at her.

"Hi. Nice to meet you." She looked at The Doctor. "You can tell you're getting older - your assistants are getting younger."

"I'm not his assistant." She scoffed as The Doctor and Sarah Jane headed off to find Mickey. "Flo!" She hissed at me. "Why did you let him drag just anyone along with him?"

"But she's not just anyone." Rose stared at me and I shrugged. "She seems nice." I said before walking off after them. I ran up to them to hear the rest of a rant from The Doctor to Mickey as he stood in a cupboard full of vacuum pack rats.

"Nine, maybe ten years old. I'm seeing pigtails, frilly skirt."

"Well, obviously they use them in Biology lessons. They dissect them. Or maybe you haven't reached that bit yet. How old are you?"

"Excuse me, no one dissects rats in school anymore. They haven't done that for years. Where are you from, the dark ages?" Rose spat.

"Um, we still used them in Leadworth." I said sheepishly, earning a smile from Mickey and The Doctor.

"Exactly." Sarah Jane smiled at me.

"Yeah but she's from some little village-"

"Anyway, moving on." The Doctor interupted Rose. "Everything started when Mr Finch arrived. We should go and check his office." He said before we headed out down a corridor, me, The Doctor and Mickey at the back and Sarah Jane and Rose at the front.

"I don't mean to be rude or anything, but who exactly are you?" Rose asked.

"Sarah Jane Smith. I used to travel with the Doctor."

"Oh! Well, he's never mentioned you."

"Oh, I must've done! Sarah Jane! Mention her all the time."

"Oh I remember!" I said, remembering back to when The Doctor had mentioned some people during our visit at the New Earth hospital. "Sarah Jane of course!"

"Well he's never mentioned her to me!"

"What, not even once? He didn't mention me once?" Sarah Jane scoffed as they rushed off, and we headed up to the door of Mr Finch's office. The Doctor soniced the door and opened it slowly as we peered in cautiously.

"Rose... you know you used to think all the teachers slept in the school... ? Well... they do." I whispered, looking at the ceiling and nodding at 13 bat like creatures hanging from the ceiling. We all retreated slowly and The Doctor locked the door behind us.

...

We hurried out to the front of the school and Mickey started panicking.

"I am not going back in there. No way." He said breathlessly.

"Those were teachers!" Rose exclaimed.

"When Finch arrived, he brought with him seven new teachers, four dinner ladies and a nurse. Thirteen. Thirteen big bat people. Come on." The Doctor said, turning to go back inside.

"Come on- you've got to be kidding!"

"I need the TARDIS. I've got to analyze that oil from the kitchen."

"I might be able to help you, there. I've got something to show you!" Sarah Jane grabbed The Doctor by the arm and towards the car park. She ran up to a car and unlocked it, opening up the boot and pulling the blanket off something covered, to reveal a metal dog.

"K9!" The Doctor said in delight. "Flo Maxwell, Rose Tyler, Mickey Smith - allow me to introduce K9- well, K9 Mark III to be precise."

"He's beautiful." I whispered as Rose gave the dog a odd look.

"Why does he look so... disco?" She asked.

"Oi! Listen, in the year five thousand, this was cutting edge! What's happened to him?"

"Oh, one day, he just... nothing!" Sarah Jane sighed.

"Well, didn't you try and get him repaired?"

"Well, it's not like getting parts for a mini-metro! Beside, the technology inside him could rewrite human science. I couldn't show him to anyone!"

"Ooh, what's the nasty lady done to you? Eh?"

"Look, no offense but could you two just stop petting for a minute? Never mind the tin dog, we're busy!"

...

Me, Sarah Jane and The Doctor sat at a table with K9 as Rose and Mickey stood by the counter. I smiled at The Doctor and Sarah Jane reminisced.

"I thought of you on Christmas Day. This Christmas just gone? Great big spaceship overhead - I thought, 'Oh, yeah. Bet he's up there'." Sarah Jane said.

"So did I actually." I mumbled.

"Right on top of it, yeah." The Doctor replied to both of us.

"And Rose?" Sarah Jane asked cautiously.

"She was there too."

"Did I do something wrong? Because you never came back for me. You just... dumped me."

"I told you. I was called back home and in those days humans weren't allowed."

"I waited for you. I missed you."

"Oh, you didn't need me! You were getting on with your life."

"I think you were her life." I said. The Doctor looked up and Sarah Jane nodded.

"You know what the most difficult thing was?" Sarah Jane sighed. "Coping with what happens next, and with what doesn't happen next. You took me to the furthest reaches of the galaxy, you showed me supernovas, intergalactic battles and then you just dropped me back on Earth. How could anything compare to that?"

"All those things you saw - do you want me to apologize for that?"

"No, but we get a taste of that splendour... and then we have to go back."

"But look at you, you're investigating. You found that school - you're doing what we always did."

"You could've come back."

"I couldn't."

"Why not?" Sarah Jane whispered. "It wasn't Croydon - where you dropped me off, it wasn't Croydon!"

"Where was it?"

"Aberdeen."

"Right. That's next to Croydon, isn't it?" Me and Sarah Jane looked at each other, sniggering before K9 sprung into life. "Oh, hey! Now we're in business!" He jumped to his feet and stood in front of K9.

"Master!"

"He recognizes me!"

"Affirmative."

"Rose, give us the oil." The Doctor said as Rose and Mickey walked off, passing him the oil.

"I wouldn't touch it, though, that dinner lady got all scalged."

"I'm no dinner lady. And I don't often say that." He said, smearing the oil over a sensor. "Here we go. Come on, boy. Here we go."

"Oil. Ex- ex- ex- extract ana- an- analysing..."

"Listen to it, man! That's a voice!" Mickey grinned.

"Careful! That's her dog!" I said before Sarah Jane smiled at me.

"Confirmation of analysis - substance is Krillitane Oil."

"They're Krillitanes." The Doctor said, shocked.

"And what are... Krillitanes?" Sarah Jane asked.

"They're a composite race. Just like your culture is a mixture of traditions from all sorts of countries - people you've invaded or have been invaded by, you've got bits- bits of Viking, bits of France, bits of whatever - the Krillitanes are the same. An amalgam of the races they've conquered. But they take physical aspects as well. They cherry-pick the best bits from the people they destroy. That's why I didn't recognize them. The last time I saw Krillitanes, they looked just like us except they had really long necks."

"What're they doing here?" Rose asked.

"It's the children. They're doing something to the children."

...

"How many of us have there been, travelling with you?" Rose asked as me, her and The Doctor left the chip shop, The Doctor walking ahead.

"Does it matter?"

"Yeah, it does, if I'm just the latest in a long line."

"As opposed to what?" The Doctor stopped at turned round, staring at her angry and hurt whilst I stood next to her, holding onto the edges of my sleeves.

"I thought you and me were... but I obviously got it wrong. I've been to the year five billion, right, but this... now this is really seeing the future. You just leave us behind."

"900 years of time and space, there's gonna be others." I mumbled.

"OH SHUTUP FLO!" She shouted at me, earning a glare from The Doctor. "Is that what's going to happen to us?"

"No. Not to you."

"But Sarah Jane... you were that close to her once, and now... you never even mention her."

"I don't age. I regenerate. But humans decay. You wither and you die." He looked at me. "Imagine watching that happen to someone who you-" He stopped suddenly.

"What, Doctor?" I asked before Rose coughed, bringing his attention back to her.

"You can spend the rest of your life with me." He said to Rose. "But I can't spend the rest of mine with you. I have to live on. Alone. That's the curse of the Time Lords."

"And what about her?" Rose nodded at me. The Doctor just stared back at her before turning round and walking off.

...

Me and Sarah Jane sat at her kitchen table at Bannerman Road, looking out the window into the night sky at the stars.

"How did you meet The Doctor then?" She asked as she took a sip of tea.

"He saved my life."

"He'll do more than that, just you wait." Sarah Jane smiled fondly. "That mans my best friend, and I can see from the way he looks at you how much you mean to him."

"He doesn't really want me travelling with him."

"Rose is obviously in love with him, she certainly doesn't want me with them. When I first met him, and then when we met again, he kept going on about my timeline. How I was something important to the universe, which I'm not."

"This is The Doctor we're talking about, if he says that, then you are. But being important to the universe doesn't mean travelling with him, time can be rewritten."

"What do you mean?" I asked curiously as she took another sip of tea.

"What I'm saying is... if you ever find yourself being thrown out the doors by Rose, there will always be a place for you here, if you want it."

"Thank you." I whispered.

...

"Flo, Rose and Sarah, you go to the Maths room. Crack open those computers, I need to see the hardware inside. Here, you might need this." The Doctor handed the sonic to Sarah Jane, as I smirked at Rose's expression. "Mickey - surveillance. I want you outside."

"Just stand outside?"

"Here, take these - you can keep K9 company." She said, chucking him the car keys.

"Don't forget to leave the window open a crack." The Doctor called back.

"But he's metal!"

"I didn't mean for him."

"What're you gonna do?" I asked as we walked towards the school.

"It's time I had a word with Mr Finch."

...

"It's not working!" Sarah Jane said as she tried to use the sonic on the computers.

"Give it to me." Rose muttered before I mouthed 'the button' to Sarah Jane and it started to work.

"Used to work first time in my day."

"Well, things were a lot simpler back then." Rose said.

"Rose, can I give you a bit of advice?" Sarah Jane asked, standing up from under the desk.

"I've got a feeling you're about to."

"I know how intense a relationship with the Doctor can be, and I don't want you to feel I'm intruding-"

"I don't feel threatened by you if that's what you mean."

"Right. Good. Because, I'm not interested in picking up where we left off."

"No? With the big sad eyes and the robot dog? What else were you doing last night?"

"I'm not, because I can see there's someone else a lot more important in his life."

"Yes, I am." Rose said.

"I was just saying how hard it was adjusting to life back on Earth..." Sarah Jane said between gritted teeth.

"The thing is... when you two met... they'd only just got rid of rationing. No wonder all that space stuff was a bit too much for ya."

"I had no problem with space stuff. I saw things you wouldn't believe."

"Try me."

"Guys don't." I said.

"Mummies."

"I've met ghosts."

"Robots. Lots of robots."

"Slitheen. In Downing Street."

"Daleks!"

"Met the Emperor." Rose scoffed.

"Anti-Matter monsters."

"Real living dinosaurs!"

"Real living werewolf!"

"The Loch Ness Monster!"

"SHUTUP!" I shouted, tears in my eyes before The Doctor walked in and looked at me. "Sorry, I tried to stop them..." I sighed as he walked over, giving me a hug.

...

"I can't shift it." The Doctor muttered as me and Sarah Jane watched him rip some wires.

"I thought the sonic screwdriver could open anything?" Sarah Jane asked.

"Anything except a deadlock seal. There's gotta be something inside here. What're they teaching those kids?"

"You wanted the program - there it is." Sarah Jane said and me and The Doctor looked round to see some alien program completely in green running across all the screens and projectors.

"Some sort of code..." The Doctor mumbled. "No... no, they can't be..." He whispered. "The Skasis Paradigm. They're trying to crack the Skasis Paradigm."

"The... God-maker. The universal theory. Crack that equation and you've got control of the building blocks of the universe. Time and space and matter, yours to control."

"What, and the kids are like a giant computer?"

"Yes. And their learning power is being accelerated by the oil! That oil from the kitchens, it works as a- as a... conducting agent. Makes the kids cleverer."

"But that oil's on the chips. I've been eating them."

"What's fifty-nine times thirty-five?"

"Two thousand and sixty five." She said. "Oh my God..."

"No, it's gotta be children. The God-maker needs imagination to crack it. They're not just using the children's brains to break the code... they're using their souls."

"Let the lesson begin." We turned round to be faced with Mr Finch. "Think of it, Doctor - with the Paradigm solved, reality becomes clay in our hands. We can shape the universe and improve it."

"Oh yeah? The whole of creation with the face of Mr Finch. Call me old fashioned, but I like things as they are."

"You act like such a radical, and yet all you want to do is preserve the old order. Think of the changes that could be made if this power was used for good."

"What, by someone like you?"

"No... someone like you. The Paradigm gives us power, but you could give us wisdom. Become a God. At my side. Imagine what you could do - think of the civilizations you could save. Perganon, Assinta... your own people, Doctor. Standing tall. The Time Lords... reborn."

"Doctor, don't listen to him." I said as he turned to me, Rose and Sarah Jane. "And you could be with him throughout eternity. Young... fresh... never wither, never age... never die. Their lives are so fleeting. So many goodbyes. How lonely you must be, Doctor. Join us."

"Time doesn't work like that!" I snapped.

"I could save everyone...I could stop the war..."

"No. The universe has to move forward. Pain and loss - they define us as much as happiness or love." Sarah Jane begged. "Whether it's a world, or a relationship... everything has its time. And everything ends."

"Sarah Jane's right Doctor." I whispered before The Doctor turned round, picking up a chair and throwing it at the screen.

...

"You've redecorated!" Sarah Jane smiled, looking round The TARDIS. It had been a long day but with the help of K9, the Krillitanes were gone.

"Do you like it?"

"Oh, I, I do. Yeah. I preferred it as it was, but uh... yeah. It'll do!"

"I love it." Rose mumbled.

"Doctor... ?" I nudged him, nodding at Sarah Jane.

"Um - we're about to head off, but... you could come with us."

"No... I can't do this anymore." Sarah Jane said, shaking her head. "Besides, I've got a much bigger adventure ahead! Time I stopped waiting for you and found a life of my own."

"Can I come?" Mickey asked, causing me to smile brightly. "No, not with you, I mean... with you." He nodded at The Doctor. "Cause I'm not the tin dog. And I wanna see what's out there."

"Oh, go on, Doctor. Sarah Jane Smith - a Mickey Smith. You need a Smith on board!" Sarah Jane said as I noticed Rose mouth 'no' at The Doctor.

"Okay then, I could do with a laugh."

"Rose, is that okay?" Mickey asked.

"No, great. Why not?" She said.

"Well, I'd better go." She said before pulling me over to one side. "The offer still stands, but if I were you, I'd stay."

"Better late than never, she'll claw my eyes out just for speaking with him." She smiled as we walked over to the doors, The Doctor following.

"It's daft. But I haven't ever thanked you for that time, and like I said - I wouldn't have missed it for the world." Sarah Jane said.

"Something to tell the grandkids."

"Oh, I think it'll be someone else's grandkids now."

"Right. Yes, sorry - I didn't get a chance to ask. You haven't... there hasn't been anyone... ? You know... ?"

"Well... there was this one guy. I travelled with him for a while. But he was a tough act to follow." I smiled at The Doctor.

"Goodbye, Doctor."

"Oh, it's not goodbye-"

"Say it, please. This time. Say it."

"Goodbye. My Sarah Jane." He said, hugging her before letting go, smiling. She stepped back a bit and nodded at me to The Doctor.

"I don't want to get in the way." I began, "And I can see that I'll get in the way of things with Rose..."

"What do you mean?" He asked.

"You know what." I sighed. "I constantly feel like I'm only here with you because of my timeline, as you always go on about, it's not fair."

"Of course you're not." He sighed before turning jokey, jabbing me in the ribs. "There's a couple onboard and I can't be on my own." He smiled before heading back inside The TARDIS.

"He needs you." Sarah Jane sighed, giving me a hug. "You know where to find me if you need me."

"Goodbye Sarah Jane." I whispered before turning back into The TARDIS.