When I first started out writing I think I mostly was just trying to make characters that were as different from me as possible. I would give them traits that I wish I had, for example Rai Kang is really smart and speaks in 4 languages and enjoys math. I hate math and at the time I had just given up learning Mandarin and was trying to learn Japanese. I'm also introverted, but most of my characters tended to be extroverted, but I might have them share one of my hobbies, but their reasons for enjoying it be very different.
Looking at all of my different projects, there's always a really fun loving happy character to be found. Some times they are a supporting character, other times they are the lead. Some are meant to be annoying, others meant to be lovable. Their intelligence level ranges from smart, average, to kinda dumb. Some are really parody level crazy, some are silly but still grounded to reality. But these characters are imaginative, leap in before looking, have an optimistic look on life, and because they are so happy they are the most fun to write scenes for. But I've also noticed recently that these are my characters that are also hiding the most pain, or going through a rough time.
Now that I've noticed this in my writing I don't know if this kind of character will continue to make appearances in future stories or not.