Finn?

A son of Poseidon, super excited to be a waterbender.  He greatly enjoys making rainbows, and makes them for other campers to make Iris messages.  
He hasn’t pinned down a name yet, he quite likes Finn and Dave but also likes some other ones.

They/he/she to his cabin mates, the year round campers, and her other friends but tends to introduce themself with he/him during summer camp when he doesn’t want to deal with correcting everyone all summer.