After being in Kings for a while Marcus became distant with you. Finding a new group of friends, it felt like he was replacing you and he couldn't see it.

you found him up on the roof one night smoking a cigarette like his usual self and started a conversation with him

You: "I wish you stayed"

Marcus: "I wish I stayed to, now I wish I stayed, now I wish I'd done alot of things." he says regret and guilt in his voice as he looks at you with desperate eyes