As per the Hat's decision, Harry gets Sorted into Slytherin upon his arrival in Hogwarts—and suddenly, the future isn't what it used to be.

::Year 2 Divergence:: What does it take, to reshape a child? And if reshaped, what then is formed? Down in the Chamber, a choice is made. (Harry's Gryffindor traits were always so much scarier than other peoples'.)

Harry Potter has been missing since he was eight. Now, seven years later, Severus Snape has a one night stand that just doesn’t seem to end. How long will they be able to keep their secrets? HPSS

Harry has had enough of seeing his reputation shredded in the Daily Prophet and decides to do something about it. Only he decides to embrace his Slytherin side to rectify matters.

Harry has learned the prophesy and he does not believe that a schoolboy can defeat Voldemort, so he decides that if he is going to die then he is first going to live.