I drew it for some kind of competition on Deviantart;)
The topic was that you should draw your OCs in the outfits of your favorite characters.
But then I did it more according to the character of the characters and that's how it came out here:


Nico as Gajeel
Alex as Usopp
Robin as Luffy
Julian as Laxus

What I think they have in common:
Nico & Gajeel: partly their personality and of course their "piercings": D
Alex & Usopp: their plump lips, almost their entire appearance, their creativity ^^
Robin & Luffy: their childish nature, of course, both love food and fun and are always in a good mood xD
Julian & Laxus: very cool personality, sometimes arrogant, but in the end becomes a friend;)