[whswhs]

I don't think you should hand out disads that either indicate a chosen ethical standard or involve a loss of self-control, especially as there are experience point penalties for not roleplaying the disad. Players can choose to give up control of their characters' actions, or lose it to an attack such as Mind Control (Conditioning) or to a Fright Check, but GM fiat will be resented.

What you can do, though, is hand out social traits. Is the character doing this stuff in a setting where their behavior will become known? Give them a Reputation: Ruthless killer, shows no mercy, -3. This will result in adversaries refusing to surrender, or even targeting them first, or in ordinary people refusing to have anything to do with the other party members because of the obvious threat. Or give them Social Stigma (Criminal Record, Minority Group, or Monster). Or even have someone pursue them, not as a formal enemy, but as a recurring threat. This might be a monster/villain/Big Bad who sees them as a threat; or a relative of someone they killed, who wants revenge or wergild; or the lawful authorities, who take a dim view of murder hobos.