I feel like Henry's warm color outfit fits his energetic and emotional character, he's active and talk too much, so his jacket and... shoes I guess you could call it, helps to sell this.
Larry works in a similar but opposite way, him constantly wearing a cape to his side helps to develope the idea that he needs shielding, like a blanket, he also uses a colorful outfit but it works on the other side of the spectrum, while Henry's red and yellow works as happy and angry, Larry purple and blue indicates that he leans more into sadness and fear, which you see a lot and fits his childish, speaking of, besides his cape, Larry's cloths design is simple, which also fits his character as a simple kid with a simple objective who sees the world in black and white, while he learns through his adventure next to his "gray" friend, how complicated it all is.
Spring doesn't have any outfit but that's only because she hasn't leanrt how to make her own clothes and has to transform into her bipedal form, so here it is.
this is 2 or 3 years into the future, I most like will change it to something that will fit her highschool teenage enviroment more, like the next ones.
now, as you might have notice, she repeats the same palette, I do that with a bunch of characters, including Henry and Larry, but inher case is because she makes her clothes for her bipedal form from her own fur and blood, which makes all the clothes either red, white, orange or blue.
lastly there's Autumn. who yeah, you can tell many thigns from her clothes, but also from her "arm".
she also uses her blood to make her clothes, but her style shows the aesthetic of a teacher or master, and her arm already tells you that she's not really friendly.
