Disclaimer: After much deep and profound brain things inside my head, I have decided that this is not mine.

Didn't like writing this chapter. Kinda difficult. Oh well.
Words in bold further down are taken directly from Deathly Hallows.

Three years later...

Severus left the Dark Lord's presence with a task. Not necessarily easy, but the old man had a way of seeing the supposed good inside everyone. The long and short of it was he had to take up the soon-to-be-vacant position of Potions teacher at Hogwarts, to act as spy for the Dark Lord. He was to convince Dumbledore that he made a mistake, anything to get him the job.

Money was tight, so a few days later he found himself staying at the Hogs Head, and had arranged to meet with Dumbledore the next day. He had his gear sent up to his room and was in the process of following it when he heard Dumbledore's unmistakeable voice issuing from one of the rooms, followed by a voice he had never heard before. From what Severus could tell, it was a job interview, so he paused by the door, hoping he could get a couple of ideas.

What he heard shocked him. Dark Lord... Rival... Power to match... Seventh month... July... Parents defied Dark Lord three times... Severus' eyes widened. The woman in there must be a Seer. No normal person could do that. Especially with that voice. Unfreezing, he took off at full speed down the stairs and to the Apparition point, and Apparated directly to where he'd come from a few days ago.

"Lucius!" he called, seeing the blonde man a short distance away.

Lucius turned, smiling. "Severus, what brings you back here?"

"I need to see the Dark Lord. Now. It's important."

Lucius looked disconcerted. "Of course. Wait here."

Severus stood, waiting impatiently. Finally, he was granted access to Voldemort.

"What is it, Severus? Lucius tells me it is important. Do you have that position secured yet?"

"Not yet, my Lord, I don't see Dumbledore until tomorrow."

"Then what, may I ask, is so important?"

Severus relayed all he had heard to Voldemort, who listened intently.

"Potter," said Voldemort, more to himself than to anyone else.

"I'm sorry, my Lord?"

Voldemort smirked. "It can only be Potter and his Mudblood wife. They have a son, I believe. He was, indeed, born at the end of July last year. He is nearing the end of his first year. The parents, they have escaped me three times. It can only be him. It fits." By now, he was definitely talking to himself. "The boy must die. And the parents, if they get in the way. But the boy. The boy..."

Severus cleared his throat. "You may go, Severus. You have been useful to me. I shall reward you in some shape or form."

He turned to go, saying as he did so, "Thank you, my Lord."

It was only as he left that he realised what he'd done. Had he known that it referred to Lily and Potter, he wouldn't have said anything. Shite.

The next day, he wound up getting the job, but it did appear that Dumbledore did not completely trust him. That didn't bother him. What did was keeping Lily safe. That was the whole point in him becoming a Death Eater, was it not?

He knew where she – they – lived, and got there as soon as he could. Thankfully, Lily was home, and also thankfully, there was no sign of her unfortunate husband or their offspring.

Lily was surprised to the point of shocked to see him standing there. "Severus," she said by way of greeting.

"Lily. I – I need to ask you, how well is this building protected?"

"Why? So you can let your little Death Eater friends in?"

Severus growled. "Lily, you are marked! You, Potter, and your kid are all marked!"

"What the hell are you talking about?"

Severus sighed, and explained. "The Dark Lord believes that he must kill your son, for whatever reason. He also said that should you or Potter get in the way, then he will kill you, too."

Lily was stunned. "Why does he want to kill Harry? He's not even a year old! Severus, what is going on?"

"He is under the impression that when your son grows up, he will have a power to rival his own, and would therefore be able to defeat him. He doesn't want to risk it."

The redhead frowned. "Why are you telling me this?"

Severus nearly yelled in frustration. "I don't want to see you dead! Sod it Lily, I loved you!"

"Loved me?" The girl was incredulous. "If you loved me you wouldn't have shoved me aside!"

"I had to! I did that to protect you! This is all to help you! Do you really think that if I hated you, I would be telling you to hide?"

"So just me? Why not James and Harry as well?"

"Bloody hell, Lily!" He was beyond frustrated now. "I know I'll never have you, and I want you to be happy! Take your family, move out of here, and hide! Use the Fidelius charm, or something. Make Black or Lupin your Secret Keeper. I don't know!" He broke off, and when he spoke again, he was quiet. "Please, Lily. Please believe me. I have to go."

He turned to leave, but Lily called him back. "Severus? I believe you. Be careful. And thank you."

"I never told you any of this." Lily nodded.

Severus attempted a smile before walking down the path and Apparating by the gate.

Severus got the job, and that September, he started his first term as Hogwarts Potions Master. Shortly after this, Voldemort announced that he was going after one-year-old Harry Potter. Severus paid a visit to Lily's house, and discovered that they had not heeded his warnings. He was furious. Did she really think that he'd lied to her? There was only one thing for it: Dumbledore.

Dumbledore agreed to have Lily, James, and Harry moved to Godric's Hollow, and placed their building under the Fidelius charms, with Sirius Black as Secret Keeper. Severus finally felt at ease. Hopefully now she – they – would be safe.

Halloween of 1980 came around, and Severus was overseeing a detention with two second year Gryffindor boys. After the detention he walked back into his quarters, sighing, and after a moment, the flames in the fireplace turned green.

"Severus?"

"Headmaster?" Severus was surprised.

The old man looked sombre. "I must ask you to come to my office. I have some news for you, some bad, some good."

"I'll be there in a moment," said Severus as Dumbledore withdrew from the flames.

He Flooed to the Headmaster's office, and Dumbledore invited him to take a seat in front of his desk.

As Severus sat, Dumbledore spoke. "I'll start with the good news, I think." Severus nodded. "The good news is that Lord Voldemort has been defeated, by little Harry Potter. A one-year-old boy did what we never could."

Severus frowned. Now what? Technically he was still a Death Eater.

"This is where the bad news comes in. The downfall of Voldemort came at a price. Harry's parents, James and Lily, were – "

"Killed."

"Well, yes," said Dumbledore cautiously.

Severus was silent for a minute, then – "I WARNED HER!" he roared. He stood up and started pacing the room, tearing at his hair and shouting as he did so. "I WARNED HER, I TOLD HER TO HIDE! SHE – ARRRGHH! SHE DIDN'T LISTEN TO ME!" He collapsed in the chair, holding his head in his hands, trying to stop the tears that threatened to escape from his eyelids. "She never believed me," he whispered. "She lied to me."

He looked up at Dumbledore. "You said you would keep her – them – safe," he whispered, almost accusingly.

"Lily and James put their trust in the wrong person. Much like yourself, Severus."

"This is all my fault. I should never have done any of this."

"Severus, please understand. Had you not said anything, no doubt all three would have died. You gave them warning, preparation, as it were. Also, James and Lily were Gryffindors. There was no way they would have given up their son to save themselves. Thanks to their sacrifice, there is now a way Voldemort can truly be defeated."

"Truly? What do you mean?"

"I mean that I don't believe he's gone for good."

"He can come back?"

Dumbledore nodded.

"I want to help."

"I'm sorry?"

"Should he ever come back, I want to help finish him off. I want to help in any way I can. He killed Lily. It's the least I can do."

Dumbledore surveyed the weak but determined man before him. "Are you saying, Severus, that you are willing to switch sides?"

"I am."

Dumbledore was silent for a moment, thinking. "I want you to appear loyal to Voldemort. Hold your position here. If – when – he comes back, you will act as a spy for both him and us. You will, of course, have to relay enough information from this side to keep him happy. But I can instruct you more on that when the time comes."

Severus nodded, and Dumbledore continued. "I must ask you, Severus, how can I be sure you are telling the truth? How can I be sure you loved Lily Evans?"

Severus stood up, raised his wand, and murmured "Expecto Patronum." A silver doe shot from it and bounded around the room. "I'll submit to Legilimency, Veritaserum, anything."

"I'm convinced, Severus. You may go."

Severus Flooed back to his quarters. He knew his Patronus had changed. It had been an otter previously. It changed to a doe the day he lost Lily, the same day he realised he loved her.

It was over. Now there was nothing to do but wait.