Little character-building HCs I like to use in my fics...
Bilbo prefers ale, and Thorin prefers wine. Bilbo doesn't mind wine and Thorin doesn't mind ale, but they both have a strong preference for the other. When they both order drinks, they have to swap as the bar tender will always assume it's the other way around.
Bilbo has been insulted many times throughout the journey, but being called a "ferret" by the trolls offended him more than anything. It's also subconsciously the reason Thorin calls him a "rat" on the ramparts later...
Thorin sleeps in, and Bilbo rises early. Bilbo is from a farming community, and hobbits would be up with the dawn - how else would they eat first breakfast at 7am every day? Dwarves are more likely to be night owls, I think, and therefore sleep in later.
Thorin's birthday is January 12th! This one was pinned down mostly by the excellent and lovely @ladyrionaofthelake who came up with a whole heap of reasons for the date, after I mentioned I thought he was a January baby, and asked if she wanted to pick the date for me to use in fic!
Bilbo is a hairy little fella - just look at those feet! He's not smooth as an eggplant under all those clothes, for sure!
Hobbit vision is better in the day, and Dwarven vision is better at night. They both have excellent hearing, but a hobbit nose isn't to be matched, and therefore Bilbo is more likely to pick up scents than any other member of the company.
Bilbo is demisexual. I always felt like he was on the ace spectrum somewhere, but this suits my personal headcanon of how Bilbo approaches romance in general. Maybe I'm projecting a little with this one, but well... I just really like the idea!
In the sun, Bilbo tans and Thorin burns. Hobbits are outdoorsy folk, and dwarves aren't, so it just makes sense that way around, I think!