My Suicidal Slytherin

This will be a Harry Potter AU to Bungo Stray Dogs, I have actually done a roleplay on this and I liked the concept of the BSD Characters being witches and wizards of Hogwarts

Dazai Osamu, a third year Slytherin student and Chuuya Nakahara, another third year student of Hogwarts, however he was a Gryffindor, a proud one at that. The two were on the Hogwarts Express, on their way back to the school that was like a safehaven for witches and wizards everywhere, unfortunately for the two of them, all the other cars and compartments were full.. They had to share a compartment together-- Granted these two were rivals in all their classes, there was only one class that the slytherin could best the gryffindor in, and that was Defence against the Dark Arts.. The two always bumped heads all the time, constantly trying to one up each other..

So what what happen if an incident on the train, caused them to have to act as lovers? Would feelings develop? Or would things get worse...