An annoying bug that I've had in the past while playing Co-op with a friend is that when any of your characters get successfully charmed by am enemy, as soon as the debuff ends, control of the character is given to the host of the game (me in this case). Initially, I had control of Roderick and Madora, and my friend had Scarlett and Jahan. By the end of the fight, I had control of every character and my friend just had to sit and watch.