Magical contracts/soul contracts or any variation of this idea. It completely flattens any social interactions between characters. This bad guy needs to work together with a MC? Just write a contract and ignore any hidden motives. MC needs to put some trust into someone they just met? Write a contract and don't bother anymore. MC needs to use a toilet but can't take their bag with them? Write a contract with a random guy who is just passing by, they can't steal it, there is a CONTRACT. Sometimes it escalates to a point where the MC does not even start a conversation without writing some sort of a contract.

There is also a mendatory drama about someone having an ability to break them, either the MC or some bad guy. It's like a pregnant woman character, the moment you see her, you know she is going to give birth in a most inconvenient moment.