I love putting in details like this, so there are little things about the characters that help flesh them out, but don't impact the plot. Examples:
Rekki is left handed (which is why her sword sheathed is on her right hip). She's also slightly long-sighted, and while she can read without glasses, she tends to need them when she needs to read a lot. Her best subject in school was maths.
Subo is vegetarian and a pretty good cook. He did a year and a half studying medicine at University, then dropped out, largely due to struggles with depression. He sometimes needs to be on meds for it.
Sarin is lactose intolerant and gets drunk extremely easily. She's always wanted to write a romance novel. Her dice collection is absolutely ridiculous and she keeps them in a wooden box that looks like a treasure chest. She hates coffee and has a bit of a sweet tooth.
Jules despises the colour yellow and prefers to wait until a clock hits a number ending in 5 or 0 to start a task. They're also gluten intolerant. If their hair wasn't tinted deep purple by their magic wavelengths, they'd actually be blonde!