Harry decided to name his and Ginny's second son after Albus and Severus because they were literally the two bravest men he had the privilege of knowing. He wanted the entire Wizarding World to know of Severus' sacrifices of protecting him through his Hogwart years.
He owed the man his life. He gave up years to spy for Dumbledore, and to make sure he (Harry) was in the right place at the right time. His last words never haunted him though. They gave him comfort that Severus is no longer in pain, and is hopefully getting along better with his parents, Sirius, Remus and Fred. He missed all of them, so very much. He wondered what they were doing on the Other Side every day.
Severus knew he wasn't going to survive Nagini's attacks, so he instead welcomed Death. He hadn't thought of it before: if he died, he would see Lily again. Even though he was dead, he still smiled at the thought.
He saw Albus, Sirius, Remus and James there, as if they were waiting for him to arrive. He looked around for his former red-headed friend, and tell her he missed her and how sorry he was for everything. James smiled at him knowingly, and motioned him to follow. Severus gave him a curt nod, and followed him to where he would find Lily sitting down reading Hogwarts: A History like she always used to do in school.
"L - Lily?" He choked and she looked up, smiling. She was still as beautiful as he remembered her to be all those years ago.
"Severus," she spoke quietly, tears forming. "I've missed you so much, Sev."
"I've missed you too, Lily, and I'm so sorry for hurting you, calling you a 'Mudblood,' he spoke the word with venom. "Then I practically sold you to the Dark Lord after over hearing Trelawney, I panicked. I tried to fix it, I swear I did. I didn't mean -" Lily put a finger on his lips to stop him from talking. She smiled, and said,
"I know Severus, I - we - should have been more careful in picking our Secret Keeper better. You didn't know as I didn't that Peter would betray us. I know you tried to fix it, and I'm glad for that. I forgive you for everything, Sev. James has seen you watch over our son for the past 7 years, and he's sorry for treating you the way he did at school," she spoke slowly, "But I want to thank you, we want to thank you for taking care of Harry. He wouldn't be alive without you watching over him." She finished with placing a kiss on his cheek.
"I can only hope Harry will forgive me for treating him the way I did as his professor," he trailed off. Then he noticed she was giving him her usual "I know something you don't know" smile, or it was more of a smirk this time. "What are you smiling like that for?"
She laughed and smiled at him. "He has forgiven you," he looked at her then crossed his arms. "Please explain, Lily." He said tiredly.
"He forgave you the moment he and his wife decided to name their second born son after you and Professor, I mean Albus."
"Harry has become a strong brave young man because of you, Severus. Never forget that. He has already forgiven you, once he found out the truth about you and Albus. He wanted to give you back something in return, for you keeping him and his friends safe for so many years."
And with that, Severus let a lone tear run down his cheek, knowing everything he has done for Lily's son has finally paid off.