Ink Ribbon Red

Six friends gather at a country house for a birthday weekend. They decide to play a game.
All six names go in a hat. Choose two, and imagine one murdering the other. Write it down. Type it up. Read it out.
Points are given for making the murders sound convincing.
Of course, when given such a task, it’s only natural to use what you know. Secrets. Grudges. Affairs.
But once you’ve put it in a story, that secret is out.
So with each fictional murder, someone gets a motive for a real one.
Which leads to the most important question: