Reasons Why I Think Killua Is An Extrovert, Not An Introvert:

reasons why I think Killua is an extrovert, not an introvert:

Killua is a people person. He’s energized by being around other people. He seeks out external stimulation and social situations and he likes to be surrounded with people. I think that’s mostly obvious in the hunter exam, the way he stayed with the group instead of venturing alone even though he probably would’ve had it easier without them to be honest, but he enjoyed the company more than anything else. Well, he enjoyed the company of Gon, but I like to think he was curious about Kurapika and Leorio as well.

Killua’s outgoing, assertive and he easily makes new friends and acquaintances.

Killua said he became “bored” with working as an assassin - extroverts tend to find repetitive or monotonous tasks/routines boring and a turn off unless they are fun or have some kind of a personal payoff.  

Killua thinks as he speaks, which is an extrovert trait as opposed to introverts who think before they speak. If you notice, a lot of times on the show Killua is shown analyzing and reflecting on a plan or a situation, and he oftentimes does it as he talks about it, like he’s thinking out loud. He rarely internalizes what he needs to say before he says it; he says it as he thinks it.

Killua doesn’t mind being the center of attention, he actually enjoys it. I think it feeds into his bravado. He has a flair for the dramatic, the way he fakes his loss in battle before he delivers the final blow, and he likes to catch the attention with his comeback wins. His little smug, victory smirks are the best proof.

Killua talks a lot. That’s not to say all extroverts talk a lot, of course, which I can confirm being an extrovert myself. It’s just that in a room full of people, we’re usually the ones filling the silence with words. And that’s what I notice Killua doing a lot, especially during the second half of the series. Once he starts talking or explaining something, he won’t stop until he says his piece. Seriously, the boy can talk. He always has something to say and he’s happy to share his thoughts and opinions with others. Between him and Gon, Killua is definitely not the “quiet” one. Gon might be louder when he speaks, but personality-wise, he’s more on the quiet side.

Killua takes great indulgence/pleasure with being the one in control and exerting his dominance over the situation. Being the “big doer” pretty much. (Best example is the Heavens Arena arc). Killua doesn’t strictly follow. Even when he easily adapts to the “go with the flow” attitude or when he follows through with someone else’s plan, he stills voices his thoughts and disagreements, and is almost 99% of the time the one in actual control of everything. He knows when to take charge, even if it’s all behind the scenes. While he follows Gon and lets him lead the way, Killua’s still the one holding the reins.

Shying away from sudden praise or internalizing his feelings doesn’t make Killua an introvert by default because extroverts can also be shy and reserved with their feelings. We all exist on the spectrum between extroverts and introverts after all; it’s not black and white. It relies a lot on our circumstances, and that’s the case with Killua. He internalizes his feelings because he wasn’t exactly raised in a place where he could externalize his feelings, that’s all. I’m not sure what his Myers-Briggs type is, but I’d say he’s either ENFP or ENTP.