What would you have done with [spoiler]?
Not your Clem, you yourself. What would you have done with Marlon if you were in Clem's position, assuming AJ didn't kill him? You have 4 options, 1 of which the game didn't give us.
- Lock Marlon up, like jail.
- Banish Marlon from the school.
- Let Marlon stay, but not as leader.
- Execute Marlon for Brody's murder (the twins' fate can factor into that or not, your choice).
It's a tough call, for me. I'll put my thought process in spoilers.
Banishment is off the table immediately. Marlon has proved himself a coward. If he got caught by the raiders and they pressed him for where he came from, he'd squeal and tell the raiders anything and everything they wanted to know about the school and kids. Furthermore, he might decide to get revenge on everyone for turning on him after he did everything in power to protect them (in his mind) and he might just go join the raiders and lead them to the school personally.
Imprisonment is also off the table, but only because of their current food situation. They don't have enough food to afford to keep someone around who isn't contributing to the survival of the group. Locking Marlon up in a room or the basement or something just makes feeding everyone harder. If they weren't struggling to feed themselves it'd be an ok solution, at least temporarily.
That leaves letting him stay as part of the group but stripping him of all authority or executing him. On the one hand, he murdered Brody. We know it was an accident, he lashed out and hit her because he was scarred of the truth getting out but he didn't mean to kill her. He meant to hit her, but we know he didn't mean to kill her. But then he tried to blame Clem for it. Again, this is because he's a coward and was fearful of the truth getting out, not only the truth about the twins, but also the truth that he killed Brody. At this point, he hasn't done anything overtly evil. He's a kid that has done things out of fear, but not maliciousness. He traded the girls but we don't know the situation. If he and the girls ran into a large group of raiders, trading them may have been the only way any of them got back at all. Sometimes you're in a no win situation and all you can do is minimize your losses. He accidentally killed Brody, then he tried to blame Clem for it, all because he was scared.
With all that in mind, I'd leave it up to the other kids. He wronged them more than me. Yeah he tried to blame Brody's death on me and locked me in with a fresh walker but at this point if I couldn't handle a single walker I'd deserve to die to it. Locking someone in with a single walker is like a minor annoyance at this point. No, I'd be fine letting him stay but he wronged the other kids at the school far more than he wronged me. He traded Tenn's sisters, which as I said, could well have been justified, but then he lied to the other kids about it for a year and made no effort to find or rescue the twins and he killed Brody, their friend. So I'd put it to a vote, let them vote if he can stay at the school with no authority or not. If they vote yes, then fine, if they vote no, I'd execute him because of the reasons I listed earlier. I wouldn't tell them when they're voting that a no vote would result in him being killed, because I wouldn't want to that to influence their decision. I would just let them vote, then act based on the outcome of the vote.