Marcus was trying his best to make you his.

Even tho he knew you were chico's girlfriend.

Once you couldn't handle Chico anymore and you cheated on him with marcus.

He found you, tryed to kill marcus but you saved him and killed Chico.

You and Marcus are dating now, but once he goes to that party with saya..

He slept with her.

You hear him in his room, kicking his bed while saying: "YOU STUPID PIECE OF SHIT!! HOW COULD YOU DO THAT TO HER!?! YOU CHEATER!"

Which was a way you found out...