Luigi is the friendly sort, although at first he can be rather shy and stuttery— but he will chat up a storm if given the chance to talk about something he’s enthusiastic about. Although Luigi is not as open to adventuring as his brother may be, he does want to become famous, and so accompanies his brother on more and more adventures. He generally loves being helpful toward others, and simply brushes it off as ‘no trouble at all’ when the person bothers to thank him for it (though he doesn’t get thanked often, so he treasures it when he does). However, Luigi is a bit clumsy in both physicality and words; although he usually intends to mean nice things, sometimes he can say something that can be misinterpreted as rude. Usually if others are offended by his words in such a manner, he is reduced to a spluttering, apologizing mess. In fact, even if Luigi does get angry, unlike his brother who tends to stay grumpy, Luigi doesn’t dwell on his bad mood long.

Although rather cowardly and timid, Luigi can gradually open up to people— to the point that he becomes a sort of ‘mother hen,’ protective and always worrying and fussing over others. Not only that, but if you mess with his friends, you mess with him. In fact, this sheer devotion goes as far as him carrying his brother in the midst of battle when he is taken down to ensure no further damage is inflicted upon him (Mario & Luigi RPG). Not only that, but Luigi’s attachment to people causes him to feel a sense of pride whenever they accomplish something— in other words, Luigi would be your biggest cheerleader.

Luigi controls both fire and electric elements, although his electric techniques, both honed in his soccer playing and in his ability christened Thunderhand, are far more powerful. In addition, the younger Mario brother has the ability to briefly run over water (Super Mario 64 DS) and to jump higher and for longer than his bro. He also makes a sort of “flutter kick” that allows him to slow his descent (not to be confused with Yoshi’s, which makes him go higher in the air). In fact, Luigi’s attack style is primarily geared toward being an aerialist. However, he also has his disadvantages— he is far clumsier, and his friction is poor, making him slide more easily. As well, Luigi has a tendency to become paralyzed with fear and step back from fighting; although, he will overcome this fear should his brother or anyone else close to him ever be jeopardized.

The theory of Luigi having turned dark due to having been trapped in Mario’s shadow is simply untrue [according to my headcanon, at least]. His Final Smash in the Super Smash Bros. tournaments is not a reflection of this, but moreso the after-ripples of Super Dimentio (Super Paper Mario). In fact, although jealous of his brother at times, Luigi adores him, and couldn’t be more proud to be his younger brother. In fact, he takes great measure to make sure everyone remembers, if not his name, the fact that his elder brother is indeed Mario— saying statements like “I’m my bro’s bro!” (Super Paper Mario).

Luigi has a minor attraction to Princess Daisy, with whom he’s even more nervous, especially with her brazen attitude right back at him. 

Luigi has a funny ability that hardly has any uses, but he still likes to show off, regardless. This ability is his ability to imitate anyone’s voice nearly perfectly. Usually, he has no use for this skill, and he still questions why he was forced to use it in the earlier Super Smash Brothers Tournaments; however, he did have one use for it in tricking Cackletta into thinking he was Princess Peach (Mario & Luigi: Superstar Saga), and it worked rather well [seriously, there was no telling his voice from hers]. He randomly uses it in conversations if given the opportunity, and his favorite voice to imitate is Mario’s.