1. Huey and Dewey are very close. Dewey is protective of Huey, because he knows what his older brother can get like when he starts thinking to much. I.E. prone to distraction. This explains why in the short when Webby threw something in the direction of the triplets it was Huey Dewey pushed out the way, not Louie.
2. Dewey’s good at remembering things about people. For example, if Scrooge told him he always likes a cup of tea in the morning, Dewey would remember that. It wouldn’t mean he would BRING Scrooge a cup of tea each morning, but he’d remember the fact.
3. He likes to make things as fun as possible. So when they’re doing chores for Uncle D, Dewey would be the first to suggest playing some music while doing so. This leads to arguments between Dewey and Donald because they have completly different tastes in music and completly different opinions about the appropiate volume at which said music should be played.
4. Kinda in connection to the above headcannon Dewey loves music. He’s practically never without his I-Pod (which is blue, of course). He likes a wide variety of music, including showtunes. Everything except classical and opera, basically. (He does however like The Phantom of the Opera, a trait he shares with Donald)
5. He can imitate his brothers perfectly, vocally and physically. When he was younger he loved to dress up as one of them and confuse Donald by acting exactly the same as the brother he was imitating for a while.
6. In connection with the above headcannon, although Dewey really wants to become his own person and not be thought as as ‘one of the triplets’ he will still imitate them, but only if he needs to. (For instance to confuse someone, i.e. Magica.) He doesn’t imitate them for fun anymore though.
7. The reason he and Webby get on so well is because she was one of the first people to see him as not just ‘one of the triplets’ and ask questions about him personally. They’re also both into theatre and musicals and they’re both quite creative.
8. Him and Louie have a ‘brother hand-shake’ they do when things go there way or Louie’s happy about something. Louie usually starts it, but occasionally Dewey will.
9. Him and Louie like art. Dewey likes looking at it, and will always admire it, but he doesn’t really understand art.
10. He does have a good eye for detail though. And a good memory. He can remember every show he’s been in, every costume he’s worn and where the pieces of the set went.