Lucidmare and relationships!
He’s easy to fluster. Though he likes physical affection, he’s often too embarrassed to admit it. He’s the kind of person to scream like a schoolgirl into his pillow and kick his legs when he thinks he’s alone. Ccino likes it because it’s endearing.
Interactions with Dream is the same as it’s always been on good days, except good days are every day now he’s not goopy. So normal brother stuff where he actively gets embarrassed by Dream and reacts to him with childish indignation. They’re also very… sibling culture.
Nightmare wants to fix Killer’s soul to be more stable and in Killer’s control. The thing is, he doesn’t know how to do that. Sure, he knows how to stabilize it out of muscle memory, but he hasn’t come up with any long term solutions.