I don't think it's a dumb idea! I think it would be neat. Unfortunately, it would be pretty difficult to implement because of some of the other systems Thread has going on. I also just have a color theme in my head for all of the characters, and Luc is blue, for better or worse. I admit it maybe was a bad idea to choose a gendered color for Luc, but here we are.
MILD SPOILER AHEAD:
If you get to a certain heart/contact level with Sarah, you unlock nail painting. The color you choose to pain Luc's nails with adds a gradient to Luc's name, using Luc's signature blue and whatever nail color you choose. In the future, you will be able to buy multiple colors of nail polish and swap between them.