I am very sorry about your brother.
Tattoos don't have to mean anything (mine don 't—I just get tattoos I like), but if you want to memorialize our brother, I'd research artists in your area, share your story when you find a good artist, and ask for ideas. The dreamcatcher has become a bit of a cheesy tattoo over the years, but if that's what you want, talk to an artist about it. They can help you come up with something.