Detention turns into disaster as Snape, Hermione, Draco, Harry and Ron are tossed 96 years into their past. Canon up to PoA, AU after. Eventually Snape adopts Harry and Draco.
This was written BEFORE it was known that Snape was a half-blood, therefore it was assumed that he was a pureblood.
Story starts in September 1994 in their fourth year (The Goblet of Fire). As they are gone, the events in that story do not happen.
According to HP Lexicon, Dumbledore was born in 1881 which would have made him about seventeen or eighteen in the 1898 school year.
Canon only applies to The Philosopher's Stone. I have used events and twisted a few things from all four books as I needed for this story. Please remember, this is AU, but it IS a STORY for your entertainment. I'm not trying to rewrite the entire series.