The Bear and Barnacle

This month, your character can only speak the truth.

Yup.

There's a general compulsion to answer any question or remark with the complete truth. They will work out eventually that there are ways to stop it - keeping one's mouth shut will do it, usually - but it works a bit like the classic truth serum, sodium pentothal, is usually depicted in films, in that "verbal tap turned on full blast until you've spilled the beans" sense: Chatty, cooperative and not quite grasping the necessary complexities of lying.

So on the morning of the fifteenth, if asked "How are you today?", your character might open their mouth to say "fine" and come out with "Tired but cheerful because I stayed up all night having sex with inappropriate people."

Fun, right?

Iago will be the one in the corner not talking.

Tag is "truth."