I think it'd be really cute if Siffrin had little nicknames for everyone and everyone only finds out about them when he's high on painkillers and fever while recovering from craft exhaustion.
Mirabelle visits "Starshine! Help me! They're trying to steal my blood!"
Odile visits "Bright moon, is it rude to tell the people next door to shut the blinding star up so I can sleep?... Oh... Can you tell them for me?"
Isabeau visits "*reach out for them but is told to put thier hands down because they're redoing bandages* MY LODESTAR! I want cuddles but I am being rudely denied!"
Bonnie visits "*in tears* Little sun I miss your cooking so much, I'm tired of eating broth and crackers"
When they're fully well, he has no memory of every doing this and curls in on themself when anyone mentions it