AU, Post HBP: Having killed Dumbledore, Snape is about to become the new Headmaster.
The Burrow, July 31, 1997
Harry tossed in his bed, unable to find sleep. A quick glance at the old plastic watch on his wrist told him that midnight was only a few minutes away. Soon he would be seventeen, legally of age in the wizarding world.
It was a good thing, in retrospect, that Ron's snores and the summer heat had effectively prevented him from falling asleep. He had a tradition to honour. Carefully, he attempted to slip out of his bed without waking his friend...but his efforts were cut short the moment his foot touched the ancient floor and it creaked loudly beneath his weight.
Ron's snoring stopped at once and he turned his sleepy gaze towards Harry.
"Just getting some fresh air," Harry reassured him. "Go back to sleep."
"OK," his friend mumbled. "Don't be too long. Long day tomorrow. Your birthday, the wedding, all that stuff..."
Ron was asleep before he could finish his sentence, and Harry couldn't help but smile as he slipped into the corridor. The Weasley brothers all had one thing in common; they could sleep anywhere, anyhow, and at any time.
He managed to exit the house without being noticed and stepped into the moonlit garden with a sigh of relief. Everything was already in place for Bill and Fleur's wedding in two days. The house was in constant turmoil these days, nearly making him forget about what he had to do after the wedding. Leave to hunt horcruxes along with his two best friends, just as Dumbledore had said.
He wasn't quite convinced that this was a sound plan, but both Hermione and Ron had acted confident in him as well as themselves...although they had no idea what was in store for them. Dumbledore hadn't had time to tell him much...
The cool wind was soothing, and walking on the grass was much more relaxing that he would have thought. He walked quietly to the border of the wards at the edge of the garden, and leaned against the high oak marking the end of the property. Somewhere, he thought he heard an owl hoot. Hedwig? Probably not.
Just ten seconds till midnight... 9... 8 … 7… 6… 5… 4…3… 2… 1…CRACK !
Before he could even murmur the traditional "Happy Birthday" to himself, Harry leaped back, fingers automatically wrapping around his wand. He knew that sound all too well; someone had just apparated, here, at the Burrow, in the middle of the night!
Trembling slightly, he aimed for the barely distinguishable silhouette a few meters away.
Whoever it was, they were obviously not used to apparating, he thought, as the mystery man immediately fell to his knees with a groan. He didn't seem about to stand up again anytime soon.
Fully prepared to fight, Harry took a step forward. It was a man, judging by the voice, entirely dressed in black, slender... the bent head didn't allow him to see the face, but the long, greasy hair, the thin frame and the clothes were familiar enough...he jumped back with a furious cry: Snape!
At the Burrow, the lights had lit up and Harry could hear Mr. Weasley and his sons shouting, no doubt searching for him. But he couldn't bring himself to care at the moment; his mind was fully absorbed by hatred for the man kneeling in front of him.
"You! Filthy traitor! How dare you?" he hissed, "How did you get in there? He sent you, didn't he? Voldemort? You think I am going to make things easy for you? You have no idea..."
"Harry! Harry, move away!"
Arthur Weasley's voice snapped him out of his trance. Behind him, the Weasley troop, wands at the ready, were rushing help. Harry didn't move and kept his own wand pointed at the intruder. If Snape's body language, bent and immobile, was any indication, the man was hurt anyway.
"Who's there?" Mr. Weasley asked loudly as he caught up with Harry. A lumos, aimed at the face of the professor, provided a quick answer. "You!"
Around them, the Weasley brothers had gathered in a menacing circle, wands aimed at the unmoving man in black.
"How did you get in there?" demanded Arthur, furious. "The wards are set to allow only Order members inside, and I doubt very much you can count yourself as such, traitor!"
Around them less flattering comments were flying toward the professor.
Finally the man raised his head, slowly, as if doing so took every bit of willpower he possessed. Ignoring Arthur and his sons, he locked his black eyes onto Harry's.
"Master, I come today to present myself as your faithful servant. Your rights on me are absolute; I belong to you in body and mind, and beg you to accept my servitude," he articulated in a slow, emotionless voice, his face impassive under the moonlight.
Stunned, Harry grimaced and took a step back.
"What...what is he talking about?" he asked with disgust, turning to Mr. Weasley.
Even under the dim light of the stars, he could see the man had turned deathly white.
"Merlin..." For a moment, Arthur was speechless, staring at the man kneeling in the grass. "He is... you are...that's impossible!"
Without a word, Snape rolled up his sleeves and presented his bare wrists to Harry. Uncovered, but not totally unadorned, the boy noticed. Two identical tattoos were circling the thin wrists in a strange, blood red pattern that seemed to almost glow on the white skin.
"Merlin," Mr. Weasley murmured again. "This is horrible...Harry you must... Merlin I didn't know that..."
Obviously unable to find the right words, the wizard lowered his wand and groaned. Around them, several Weasley brothers let out a murmur of protest in response to this sudden show of trust.
That was the moment Molly Weasley chose to rush to the rescue, wand in hand.
"Arthur, what is going on? I called the Order, they are on their way!"
"Molly, go back in the house," Arthur said in a firm voice that Harry had never heard him use before. It didn't prevent the plump witch from approaching the silhouette kneeling in her garden.
"Who...Severus Snape!" she hissed, not even trying to hold back her fury. "How dare you..."
"Molly, enough, it's complicated," Arthur cut her off, taking her by the shoulders. "Severus had to come, he didn't have a choice."
"I don't understand," said Harry. Snape's silent stillness was every bit as nerve-wracking as the odd behaviour of Ron's father. "What did he mean? Why is he even here? Shouldn't we tie him up or something? We should at least take his wand!"
Mr. Weasley opened his mouth, but before he could speak, Snape had removed his wand from inside his robes and laid it on the grass, at the feet of a stunned Harry.
The pale moonlight played on the strange pattern tattooed across Snape's wrists and Harry heard Mrs. Weasley gasp before stepping closer to her husband.
"This is the 31st of July, Molly. Harry is seventeen." Then, turning to face Harry: "Happy birthday, my boy."
By the tone, Harry could sense that this birthday was off to a less than stellar start. Glancing at the circle of Weasley brothers, he noticed that Bill and Chalie had both lowered their wands and were now pensively watching Snape. Fred, George, and Ron, on the other hand, were still aiming their wands at their former potions professor, all the while observing their parents, trying to ascertain exactly what was going on.
"He needs to know, dad," Bill finally said. "Tell him."
Arthur Weasley shifted on his feet, obviously trying to find the right words before turning to Harry.
"Harry, you realize you are now of age in the wizarding world, don't you? You've been seventeen for several minutes now," he started awkwardly.
Harry nodded, intrigued. Where was this going?
"Well, this is a very unexpected turn of events, one that goes along with your new adult status..." He paused, taking a deep breath.
It was a low and cold voice that took over his speech, startling the entire audience. Snape, apparently, had decided to take the matters into his own hands.
"You, Mr. Potter, have just come into possession of a part of your inheritance," he explained, staring intensely at the boy. "That is, if you accept it."
"I don't get it," Harry struggled to understand.
"It's quite simple," Snape started again, although without any trace of his previous professorial impatience. "I belonged to your parents. After their death, as an underage wizard cannot own a slave, the authority on my person was transferred to Albus Dumbledore, as stipulated in your parents' will. As you are now of age, you can now claim me."
His speech was met with four gasps of surprise.
"You are... you are..." Harry stuttered, unable to pronounce the word.
"A slave," Snape helped him out. "At your service."
If there was a hint of irony in his words, it was drowned by the resignation plainly showing on the wizard's face.
"No!" Harry suddenly shouted. "No, no way! I won't do it!"
Snape's face tensed slightly, but it was Arthur and Molly Weasley who flew to his side.
"Harry, no, you can't make this decision just like that! Think about it!" cried Mr. Weasley, who looked rather panicked.
"You are kidding me, after what he did to Dumbledore?" Harry shouted back, before an idea hit him. "Oh. If I take him, then Voldemort can't use him anymore, right?"
"Yes, that is true, but it isn't the point," Arthur tried to explain. He was sweating in spite of the cool wind.
"Well, I think it is," Harry snapped, annoyed, before turning to Snape. "What more? What will you do, if I refuse? Go back to him, become headmaster of Hogwarts, and torture students?" he spat.
But Severus Snape remained impassive as he answered.
"If you refuse my servitude, M. Potter, I won't go anywhere. I will die."