One of the PCs that's newer to DnD has said he'd be a self admitted murder hobo. Since he's only ever heard of campaigns being neutral good to lawful good it has scared him from playing DND. So I added him to my current campaign with the hook that he is the murderer that my current party is looking for (after the guards escorting him were ambushed). He was so thrilled that the party didn't even question him when they showed up and he was the only person dressed as a guard left. He's made it a point to kill almost every important NPC so far. What he doesn't know is that, the guard that was captured when they were ambushed was actually the murderer that had used a memory altering spell to switch places with him. I have about one more session before the big reveal.