I always thought of Mario as arrogant yet heart-loving at the same time. Luigi may show his personality more since he is not the one thats always controlled but its pretty fun determining Mario's character.
Sometimes Ive even thought of him as lazy, like in Super Mario Sunshine, the guy sweeping around in the hotel where the ghosts were at asked Mario if he could use a vacuum to get rid of them, and later he said "What, why are you looking at me like that?" but that could have reminded him of Luigi..but who can really blame him since he was forced to clean an entire island up....
I honestly think a lot of things change for the characters because of whoever is running the game. Like Luigi, isnt he supposed to be known as the intelligent type? the "Mario is brawns and Luigi is brains" thing but however it doesnt show very much in the ML series, and they make him more of a goof instead. I may be wrong though since I havent really fully played both of the games >< Thats why I think its just whoever is managing the game >_> It gets on my nerves.
In one of the MPT trophy sequences (I forgot the character who wins ><) Luigi falls and Mario (along with Peach) tries to help him get up, however Mario doesnt do a thing in M and L when Luigi gets hurt. Then, this isnt much but in the title screen for Luigi's Mario Party theme Wario is trying to attack Luigi and you can see Mario aiming to pull him back, and for MT64 he jumps in when Luigi is about to fight Waluigi in the opening sequence.
Oh, and didn't the Star Gate in PIT mention in some way that he cares about luigi?
Well, ok I hope I wasn't going off its just everyone seemed to be discussing whether he cares for luigi or not..
Mario has all kinds of traits to me though. Like..he's hyper, but also has a bad temper on some cases. Nintendo of Europe released his public diary a few years back....when they were celebrating his anniversary or something, and each page had Mario summarizing one of his adventures. One of the pages Mario even admits he gets tired of Peach getting kidnapped, but he still does it anyway and thats what makes him so kind hearted. And then on another diary entry, he was talking about when he met Lord Crump and called him a Son of a gun. I'd never expect mario to say that o.0
NOE could have just done that for fun but they made it seemed like he really wrote it from the advertising. but dont jump me or anything >< I'll try and look for it again if I can.