Harry runs away the summer before 2nd year. He is missing for many months before Snape tracks him and brings him back to Hogwarts. Having been kicked out of school, the only way he can stay at Hogwarts is to become an apprentice. Snape reluctantly agrees to take him on, but circumstances get complicated and the two end up having to go into hiding, forcing them to get closer and bond as a father & son. This is Severitus-style fic focused on Harry and Snape and a few OCs.