Judging by his profile tag, Rino is from Holland. Rino, do I correctly guess that you are not a native speaker of english? Apologies if I'm mistaken in that guess, but it might be that you found something in my wording funny.
I wondered about Dter's action when I read what you posted for him with regard to attacking either Cheal or Frane, but figuring that you knew your character best, I went with Dter attacking Frane because you'd said he'd attack whichever of the two of them was closest, and Frane was. I also took into consideration that Dter is NE. While I confess I wasn't sure what exactly you were up to, I allowed the attack on Frane even though I was hesitant. Next time, if I'm hesitant, I will pop into the OOC to ask.
Regarding player vs. player combat, I don't care for it. I said at the start that any alignment would be acceptable, and I meant it, but I also stated at the start that regardless of alignment there would need to be an emphasis on getting along and working together. That said, your characters are your own. I am willing to adjudicate player vs. player combat, but on a short leash and I certainly won't tolerate it over the long haul. If that sort of thing goes on, PCs will probably end up becoming NPCs. I don't mean that rudely, but there you have it. I'm not expecting it to become an issue, though. You all seem very reasonable.
To rectify the situation in the IC, I can edit Dter's action so that he does not attack Frane. We're just starting off and party cohesiveness will be important; it'd be a shame to spoil cohesiveness simply because of meta-miscommunication. If you don't want to go the editing route, then Brakkus is free to react however he sees fit. I'm open to any other ideas for a fix that you might have.