Officially, Severus Tobias Snape was dead.
And that was exactly what he wanted the Wizarding world to believe. It was easier that way, being dead, it allowed him to get away. While he knew that certain stubborn Gryffindors would see to it he was honoured as a hero, something he might have wanted at one time, but after everything, a simple life seemed the better option now. Definitely somewhere outside the United Kingdom, where he could relax and not worry about being recognised, maybe have a chance at real love in all its forms, be it friends or a lover or a family all his own. He doubted the latter would happen, that sort of thing eluded him long enough that likely, it was never going to be.
Taking a passed down page from the Pureblood grandfather he never knew personally, Severus spent years building up his body's immunity to various poisons, including Nagini's after the Dark Lord's return with her in tow. Of course, healing the wounds and keeping potions for blood loss and injury on his person at all times was also helpful, it couldn't diminish his naturally developed responses. The key to fooling everyone was a simple Golem, set to take on his appearance at a moment's notice. It was a few hours after he was left alone, the sky still dark and ominous, and an ache through his body which he knew would take some time to completely be rid of. There wasn't as much blood as he expected, and the hole left in his neck needed tending to, but not before activating the Golem. Careful to not disturb the marks of the floor best as possible, he stepped away from the scene of his 'death', taking in how the setup for whomever would come upon this scene later, if anyone cared enough. Severus was too cynical to expect that Potter, Weasley, or Granger were going to return to this building for his body once they secured victory, if they won at all, although that is no longer any of his concern.
He was almost angry at himself for the weakness shown when he begged Potter to look at him, felt almost as if he'd been laid bare for just a moment. Certainly he couldn't show any pride at these children for being able to survive such atrocities at the surface, but he'd wanted to. Weasley and Granger were mostly hidden from view, but he noted with satisfaction that they all seemed honestly appalled by his 'death'. At least now he had done what he promised Dumbledore he would, and in leaving those memories, he had also completed a post-mortem promised to Lily to make sure her son was safe. Somehow Severus knew Harry Potter would survive the Killing Curse one more time, and in it, ensure the end of Tom Riddle.
In the Dark Lord's actions, Severus had been set free, and he wasn't going to fuck up this chance, not when everything was in place for him to make a great escape, no matter the outcome of the night.
Over the years, more often since Potter started at Hogwarts, he began the plan to disappear sometime after taking on the Potions Master position. The idea was that, since no one in the Wizarding world would look for him in the Muggle world, he had made legal documents and a bank account in his father's name, which was easy given the man died many years previous from alcohol poisoning some years after his mother's passing. Without question and with discretion, the goblins would then take however much he asked for, converted and deposited it into the Muggle account on a somewhat regular basis. Most of it just collected interest, some went to bills and taxes on Spinner's End, paid timely and regularly. However, since the beginning of that school year, the property was no longer a drain, for the small one it had been, as he sold it back to the bank. Something about building on the site and needing everyone to sell, which he was more than happy to oblige, and the timing couldn't have been better. He didn't know how long selling the dilapidated home would have taken, but practically giving the land up for more than it was reasonably worth made his plan easier to execute.
Now there was less tying him to the past, as he stood in the broken doorway of the shack, more than before. Getting a passport for international travel in his father's name was also easier than he thought it would be, but that had more to do with how distanced he'd become with the Muggle world. With Hogwarts and Hogsmeade so far from any Muggle town, he had to Apparate somewhere closer, Dundee or Perth being the best options, and get himself back to Manchester, where he had the last of his things collected. After that, he would go onto London, to Heathrow, to go anywhere he felt like. A whole new road ahead, and in the darkest hour of the day, he ran to a safe point of departure, ready to leave the world that was once home, and start his life over.