Everything you need to know about Dink you can tell by his name. After all, can you imagine a jerk named Dink? It’s impossible. Just from his name you can tell he’s a good guy. Sure, he can be a little strange – like with the zero gravity skinny-dipping – but, hey, everyone needs a hobby and once he explains why he does it, he sounds like the sanest person in the Battle School.
Dink also seems to be the only student who realizes that the game they all care about so much…is just a game. (Of course, he still loves it because it’s zero gravity laser tag – what’s not to love?)
In some ways, Dink is Ender’s real second commander, after Bonzo. That is, while Rose de Nose is the commander of Rat Army, Dink leads a toon and he leads it pretty independently of Rose. As such, Dink is useful here as a counterweight to Bonzo. Whereas Bonzo was inflexible and had his drills, Dink believes in keeping things loose. Whereas Bonzo would never listen to Ender or take him seriously, Dink adopts Ender’s way of doing things (because they work). And whereas Bonzo takes himself and the game very seriously, Dink knows that it’s just a game. (Oh, and one more: whereas Bonzo wants to get rid of Ender, Dink specifically wants Ender on his team.)
Dink is a useful opposite to Bonzo. Which may explain why, when Bonzo goes to kill Ender, Dink is the one who shows up to try to stop him. Even after Ender leaves Dink's toon to head up his own army, he remains friends with the guy, and even shows up at the end as one of Ender’s squadron commanders.