this is rovian kirishima, a character from yugioh go rush. (the blonde in the corner is a big fangirl and friend of hers) she's presumably 11-12 and a leader to a group of bandits.
she is a guitarist as well as a poet, she's been interested and participating in these hobbies since she was small. not nearly as long ago, rovian was introduced to rush duels and holds them to incredibly high regard and intensity as the former two things. all these interests of hers could be labeled as special interests. while other characters may have things in particular they're obsessed with, rovian's near constant desire to be participating in at least one of them both inhibits and assists her ability to communicate and relate to others.
the vast majority of the time, she speaks in "poems" that she comes up with the spot which others may find incomprehensible or difficult to talk her. she inserts very random words, syllables, onomatopoeias, similes, english phrases, and generally "artistic" sounding manner of speaking. she also tends to have a strange affect to her speech, a "sing-songy" tone that is noted to occur with autistic people.
though rovian primarily uses her poems to communicate, at times will use meaningless repetition of certain syllables and noises seemingly just talking to herself much like vocal stimming behavior
another form of stimming she does is physical stimming. she keeps her guitar on her person at all times, and is regularly strumming it, especially in high emotion. arguably, it could be said she is just playing with her guitar but with how frequent it is, it seems to be stimulatory and self soothing. often she accompanies her poems or vocal stimming with strumming her guitar as well. usually she uses the same tone over and over so it feels to me less like creative expression, moreso another part to how she communicates using the things she likes and stimming
she also exhibits black and white thinking, (more accurately i'd call it an all-or-nothing mentality, black and white makes me just think of morals which isn't always the case). this is what leads her to dislike the protagonists. with little evidence or reasoning besides off remarks and misunderstanding their actions, she assumes that they're greedy and out to ruin everything that she enjoys about rush duels. this also leads to another aspect of her, which is difficulty in emotional regulation. she's quick to immediate anger and impatience over anything that upsets her, literally having an "ability" of sorts called patience-limit mode where her eyes and hair turn red as she becomes enraged
overall, even if it's not intentional she reads as a very autistic character to me. as someone who also speaks weirdly it's heartwarming to see her poems be encouraged and understood by people around her.
there's one instance of this i really like, which is when her cousin london talks to her in the same manner that she does. you can see it here it makes me very happy