Doesn't Cody start to show some of the same serial killer tendencies Dexter had as a kid in the books? For some reason I remember it being Cody who tortures and kills the annoying neighbor's dog that Rita just ended up giving away in the TV series. It'd be interesting to see something along those lines develop next season as another thing Dexter has to worry about at home. He's already shown a bit of a violent spark by getting into fights this season, and his history with his biological father (seeing him rape and abuse Rita in the past, etc.) would make for a believable trigger, like Dexter seeing his mom get cut up.