The usual disclaimers apply.
Goblins had always been hard to deal with. However, with a little trick and the fact that Sirius Black had been the last living, free relative of Bellatrix Lestrange, the goblins accepted that he simply had to enter her vault. Nobody but Albus knew for sure how he had figured out that Bellatrix Lestrange had been in possession of a golden cup that had allegedly belonged to Helga Hufflepuff and which Lord Voldemort had turned into a Horcrux and he did not even tell his wife. He did not tell anyone either how he had found out that there was a diary at Malfoy Mansion.
However, it came as a surprise to everyone when Augusta Longbottom carried the head and body, separately, of a snake into Hogwarts. She had told everyone who wanted to hear it (and all those who did not want to hear it, too), that the snake had come straight into her classroom one morning and that she had, with the little help of magic and a little help from a sword she had borrowed from Albus Dumbledore to teach the three children, Harry Potter, Luna Lovegood and her own grandson, Neville Longbottom, about the founders, chopped its head off. The children weren't truly disturbed, she would tell everyone afterwards. Quite the contrary. They seemed to think it fascinating how there was a little puff of smoke and then the snake was just dead.
Augusta Longbottom was especially proud of her grandson – he had looked at the snake, even before it was dead, and had then, proudly, helped carry it out. He had showed bravery, in face of the living, and the dead snake. And of course, she was extraordinarily proud to rub it in towards Minerva McGonagall that she had killed such a huge, living creature.
The rest was, as they say, history. Somewhere in the forests of Albania, the spirit of Lord Voldemort tried to gain power, made the mistake of trying to push himself towards Scotland and on the way there, in the middle of the English countryside, tried to find refuge in a large house that was called Malfoy Mansion. His spirit was vanished by a frustrated Narcissa Malfoy who was sick of boggarts and other spirits roaming her house. As she wildly waved her wand around, she wasn't aware that Lord Voldemort stuck between boggarts, spirits and ghosts and was vanished with the rest of them. It is told that they never knew what happened.
And thus went died Tom Riddle forever. It wasn't very spectacular and unknown to most of the world and wizarding kind.
Which of course, would not have made it simpler for one Harry James Snape, who used to be Harry James Potter. Wizards and witches believed that he alone had vanquished the former He-Who-Must-Not-Be-Named. However, he had a smart adopted father, who kept him away from this, who told him, bit after bit, what he had done, what had happened and why people would react to him the way they would. And because Harry Snape was influenced heavily by his father, he sneered it off, or rather scowled it off and ignored it.
He was a happy boy, most of the time. There were hitches, of course.
The first one had happened when he had gone to see his Tima and had found her, hugging none other than his godfather. He had then run away, naturally, and it was only due to his love for Tima, that he slowly, very slowly, warmed to his godfather. He knew that he would never love him as much as he loved his Papa or Tima, or Minerva, but he liked him. To play with, sometimes. And he had to accept him because he was there most of the time when he went to see Tima. Even though he really didn't understand for a long, long time, what the appeal of snogging exactly was – and he refused (influenced by his Papa) to carry any flowers or rings or throw flower-petals or do anything extraordinary when his godfather decided to marry Septima (by that time, however, Harry was old enough that he had four front teeth and could say Septima perfectly). He was there, though, with his Papa. And he ate cake and good food and was even allowed to dance with Septima and Minerva. And then, later, he would even sometimes be with Septima when she nursed her new baby Aleph. Harry could never understand why people gave their children such strange names – and he had a good laugh with his Papa about it.
Minerva enjoyed her grandmother status with Harry. She saw him most every day, she taught him what she knew about Transfiguration even before he entered Hogwarts and she enjoyed being around him. Even when he tried to get her to play football. There were still times when she exploded and fell hard into her brogue – especially when Peeves and Harry played one of their tricks on her or on other staff members. Mostly harmless, yes, but nevertheless tricks and she was maybe the first person in Hogwarts-history, who handed out a detention towards an eight-year old. Who would have thought Harry had it in him to plan, together with Peeves, to bombard all students in the Great Hall with Stinking Bombs and to actually go through with it? And that on the first day of term.
As for Severus – his life changed and he felt himself changing, ever so slightly, with it. One day, he even talked to Lila Lovegood as he brought Harry to Mrs Lovegood (and that had happened before the snake-incident). And found himself talking to her the day after. And the day after. It took him, however, two years to ask her out and only after he left Hogwarts for good, he felt freer to go out with her. Severus did leave Hogwarts. He was free of any obligations towards Albus Dumbledore. His only obligation was his son. And he made damn sure he took good care of him. So Severus left Hogwarts, bought for himself, and his son, a little cottage in Kent and settled there, writing books about Defence against the Dark Arts and Defensive Potions. His books were a huge success, usually, because, well, people seem to like the kind of acerbic humour if it's written down and not directed at themselves.
Lila Lovegood moved in just shortly after Luna started Hogwarts a year after Harry – and Severus would always say that she had been lonely and that had been the reason they moved in together. However, for everyone who ever caught them in a private moment, they knew this wasn't true. They were the perfect example that opposite attract. Lila wouldn't let Severus fall into one of her moods and she never failed to make him smile (or laugh, on occasion) and Severus never failed to bring out the serious side in her. Nobody apart from those two knew how they had fallen in love – but they had. Even though Severus would always deny it.
But – often, he would think about how this all had come to pass, how he could not stand the thought of the boy, in whose hands his fate had lain, being raised by one evil Petunia Dursley and how he had been made, how he had made himself to let the boy in. And how he had changed his life. How Harry had made him love him. How Harry had taught him how to love again.
Harry didn't mind that his Papa was with a woman. He knew he always had his Papa when he needed him and he was busy being at Hogwarts anyway. He knew he could count on the ghosts, on his friend Peeves, on most of the teachers and on his friends.
Only sometimes, Harry would think how different it all could have been if that one day, his Papa, Professor Severus Snape, 'fesser Snape, 'fesser Papa, had come for him and how grateful he was, that he had his Papa.