Douglas and Martin have a fairly good working relationship in the flight deck, but they complement each other perfectly when they kill people together, using MJN's random and unpredictable destinations to minimize the chances of their murders being linked to each other. They didn't start out as a team, but it didn't take them long to instinctively know the other man is just as screwed up.

M/D or gen with incredibly close friendship (because I assume you have to be really close to someone if you want to kill people together), I have no preference as long as there are murders and they commit them together.

I'm so glad this is an anon kink meme /)_(\