A/N: So this chapter title and the title of this fic is "Promise of a Lifetime," obviously. It is based on the song "Promise of a Lifetime" by Kutless. It is an amazing song. Honestly, you should check it out. The last paragraph in fact features some of the lyrics.

Promise of a Lifetime (DaughterOfAres)

With his mother in the kitchen drinking a cup of coffee, Harry set out for the entrance to the basement where Snape still was five hours after their midnight awakening. He realized it was rather foolish to go down there. Snape had made it clear to everyone that he wanted to be left alone. However, Harry just couldn't do that. The man was obviously hurting by his father's sudden appearance.

"Um, sir, it's me," Harry said hesitantly, walking down the steps into the dark and damp basement. He then winced when he saw Snape's eyes staring at him. The man clearly wasn't happy with him coming down here. "I guess you realized it was me."

"Yes," Snape replied, elongating the word. "Your mother would know better than to disturb me."

"Yeah, I bet she would." Harry then tugged on his shirt collar.

"What do you want, Mr. Potter?"

"Well, do you want to talk?" Even before he said it, he knew how stupid it sounded.

"About my father being a bastard on parole? No, Mr. Potter, I don't want to speak about that least of all to my student."

"What about to Lily's son?" he asked, giving Snape a pained look as if he expected a blow at any moment. Harry instead heard a soft laugh followed by the man muttering something under his breath.

"Fine, Mr. Potter, you've convinced me." He then motioned with his hand towards the stool beside him. He said nothing when Harry sat down. "My father has a drinking problem. He's had it for years. Sometimes, it caused him to lash out at my mother and me. Yes, he has hit me on occasion. All accidents of course," Snape said derisively. "Or so he claimed. When I was a first-year, he left me and my mother, abandoned us without so much as saying a word beforehand. Was I angry about this? Honestly, no. I wasn't angry. I was disappointed, but not angry."

"Okay," Harry replied, not knowing anything better to say.

"I appreciate the thought, but go upstairs. I'll be fine."

"Yes, sir," responded Harry, standing before heading back. He stopped at the base of the stairs, though, and turned around. "Sir, can I ask you a question?"

"Ask," Snape answered, not bothering to turn around.

"You and my mum, you love each other, right?"

"I do."

"And you two have been sleeping together since, what, the start of the month?" Harry stood his ground when Snape whirled around and stared at him.

"I don't see how that is any of your business, Mr. Potter," Snape quietly said.

"Well, it's just, I guess, well, are you going to marry her, sir?"

"Marry Lily?" he repeated softly, staring at Harry with an indescribable look. "I suppose if we continue our relationship that I will ask someday. Why?"

"It's just, well, I'd be cool with it, sir," he said, shrugging.

"You'd be 'cool with it," repeated Snape slowly.

"Yeah, you know if you asked her to marry you. I suppose you're not the worst guy in the world to be married to my mum. You make her happy after all. Isn't that the main reason people marry, because they're happy and ready for the next step?" Harry then laughed awkwardly. "I mean, from what I've gathered so far during this whole thing, you've been in love with my mum since you met her when you were like nine. I think that's called like childhood sweethearts or something. And well, they say that if you marry your childhood sweetheart, your marriage usually lasts longer."

"They say?" asked Snape, folding his arms. "Who is 'they,' Mr. Potter?"

"You know, they, people, researchers maybe, I don't know. It's just they."

"I see. Well, thank you for giving me your blessing, but I honestly hadn't thought about it."

"Really? I'm mean, with all due respect, sir, you two aren't getting any younger."

Snape glanced at the young man before chuckling. Leave it to Harry to point that out. Frankly, he had thought about it, but, well, Harry did have a point. They weren't getting any younger. With a sigh, he inclined his head in gratitude before turning back around. Smiling a moment later, he thought how far he had come to letting a fifteen-year-old tell him what to do about his love life. But it was a good idea after all. And it wasn't so upsetting to think of asking the beautiful red-haired witch to be his wife.

~POL~

Drawing in a deep breath, Snape glanced around the kitchen. He mentally went through his checklist. Harry sent off to the Weasleys for the night, check. Chicken Alfredo served onto the plates with a basil leaf on top, check. White wine poured into two glasses, check. One long stemmed red rose in hand, check. Candles lit, check. Engagement ring still locked up in the black velvet box in his pocket, check. Everything seemed to be finished. Now he just had to wait for the hopefully soon-to-be-bride to come home from work.

When the front door closed, his heart leapt up into his throat. His stomach lurched, and his breathing went shallower and shallower. What if she said no? What if she started to cry? Gritting his teeth, he shook his head. She wouldn't say no. Well, she might say no because she might not be fully over James yet, but she wouldn't be upset with him for asking. It was logical to take the next step.

"Whoa," Lily softly said, walking into the kitchen. "What's the occasion, Sev?"

He only held out his hand. He was rather convinced if he even attempted to speak right now that it'd come out as a series of unintelligible gurgles. He smiled softly when she took his hand automatically without a drop of hesitation. He gently led her to her chair and held it out for her as she sat down.

Unable to wait any longer, he dropped to one knee beside her and slowly pulled out the black velvet box from his trouser pocket. His heart pounded loudly in his ears, blocking out her gasp. He stared at her face throughout the entire thing, taking in every movement as he slowly opened the box.

"I realize this is sudden, and I apologize for—" Lily's lips instantly covered his, silencing him within moments. He'd hope her kiss meant yes because he honestly wasn't sure if he could attempt to ask her again. He then laughed when she fell completely on top of him, sending them sprawling onto the kitchen floor.

"I, Lily Evans, humbly accept," she replied, biting her bottom lip before capturing his lips again.

~POL~

At the end of August with hundreds of families around, a happy trio stood off to the side by the trains. Smiling widely, the redheaded witch adjusted the fifth-year young man's collar for what seemed to be the hundredth time that day as students past by to get onto the train bound for Hogwarts.

"Are you sure you have everything, love?" Lily asked again.

While his mother fussed over him, Harry rolled his eyes. He couldn't help but smile, however. It felt nice to have a family that loved him, seeing him off this year.

"Lily, leave the boy alone. Your mollycoddling is embarrassing even me," Snape said from behind his fiancée with a small smile and a wink to Harry. "Lily!" he suddenly exclaimed as Lily reached her hand back and smacked him in the sternum. He rubbed the spot as though horribly injured.

"Honestly, Sev," Lily said. There was a slight tremor in her voice as she pulled Harry to her for another hug. "I'm not going to see him for ages, and you're going to see him every day."

Snape rolled his eyes, but remained silent as he placed a hand on Lily's shoulder. After all, she was clearly exaggerating for the boy, who still wasn't made aware that his mother would in fact be at Hogwarts this year with them. He still wasn't sure why Lily hadn't told her son that he had asked her to move in with him in the dungeons. Perhaps because she, like him, thought Harry would be horribly embarrassed by that fact.

"Mum," Harry whined. His mother's grip was suffocating, and he was sure everyone at the train station was watching. Okay, so he'd admit it. He truly loved the attention.

"Sorry, dear," she replied, releasing him. With her arm wrapped around his waist, she took a step back to stand beside Snape. "Behave. I don't want to hear about any stupid stunts. Listen to your teachers. And make sure you study hard. I also expect you to write me once a week." She then engulfed him in another fierce hug. "Oh, I'm going to miss you." Her hand then smoothed down his messy hair lovingly. "You know how much I love you, right?"

"Yes, Mum, love you too," the young man replied before glancing at Snape. "Are you coming on the train, D—er—sir?"

"We aren't in class right now, Harry. You can still call me Severus." He then smiled a bit more. "I'm just a stepfather who would like a hug from his soon-to-be adopted son before he goes off for another term," he said, while pulling Harry to him for a hug. "And to answer your question, no I'm not going on the train. Would you really want me to, though?"

Harry shrugged, pulling away from his soon-to-be adoptive father. "Doesn't matter to me," he replied noncommittally. "It's not like I'll be able to avoid you all the time at school."

"True. I trust you remember what we talked about last night?" he asked. His tone had taken on a sterner quality, while his eyebrow rose towards his hairline.

It wasn't easy, but Harry managed not to roll his eyes. "Yes, sir."

"Good. And you understand, correct? That despite how harsh I may be on you or your friends in class that you are my son and I love you?"

"Yes, Dad, I know. Though, if you felt inclined to go easy on me when grading my ess—" Harry didn't get to finish his sentence as he was spun around and pushed towards the train. Laughing as he started to climb onto the train, he called over his shoulder, "Love you too, Dad."

Smiling back, Severus Snape, bastard of the dungeons or Dad nowadays, wrapped his arm around Lily's shoulders, watching as the other children boarded the train.

"So, we have two hours before we have to be back at the school, right?" Lily asked innocently.

"Yes," he said, kissing her cheek. "Would you like to have tea in London before we leave, Lil?"

"No, not tea, but there is something else I'd like." Her smile then widened as she gave him a lopsided grin. Her green eyes were alight with badly hidden amusement.

"And what would that be, Li—" Snape then yelped and his eyes widened as a hand cupped his backside none too gently. He couldn't believe it. That sly little witch had just squeezed his butt in public! He wasn't sure if he should have been outraged or demanded she do that again.

"I'll give you three guesses, Sev," Lily teased, turning back to smile and wave at the train.

That damn train took forever to leave the station. However, Snape stayed and waited with her in a sideways hug. Who'd have ever guessed this? When he learned his Lily had been murdered fourteen years ago, he had fallen to his knees and sobbed for hours. She had promised that day on his porch to be there always with him. While being married to James she hadn't been there, she was still alive for him to be there for her always. Sighing, he closed his eyes. His promise of a lifetime had finally rung true.

A/N: I sincerely hope you enjoyed my attempt at writing a Severus/Lily fic and will leave a review concerning your thoughts on this fic. Thanks for reading. :D