I just had an entire chapter (more of an intermission, really) come to me in the shower.
Current bad guy's about to be killed off, so I decided to introduce the new bad guy having a meeting with their boss (the Elf Queen). He's actually not that bad, and kind of relatable- he's an elf, 4,000 years old and riddled with cancer and advanced dementia. But because elves use magic to extend their lives (they aren't naturally immortal in my setting), he's basically carrying on like nothing's wrong. But all it takes is for him to step on a rusty nail (what with iron dispelling magic) and all his enchantments will come undone, and he'll die on the spot.
What was even more fun was that I finally got to introduce the Elf Queen's elite guard, the Changelings. They're humans, brainwashed and raised from infancy to be loyal to the Elvish cause, and even trained in the ways of magic. And their names are John, George, Paul and Richard.