However, lacking that understanding doesn't make him indifferent to Emil's distress. Uta Frith describes this as "instinctive sympathy": perceiving a person to be sad=>do something to cheer them up, regardless whether this is an appropriate thing to do given the situation/the reason they are sad. So yes, Lalli remembered that Emil cares a lot about his hair, but he wrongly assumed fixing it would brighten Emil's mood due to poor theory of mind.
Okay, late answer, comment, reply (?), but this is something that has been bugging me quite a bit, not least because this kind of thinking has led to various people not understanding me IRL even without a diagnosis to blame their lack of understanding on (I'm honestly afraid what will happen if/when they have one).
For one thing, given Emil's reaction beforehand I'd assume it's extremely unlikely Lalli didn't know that the troll was what upset him, the problem I personally would think Lalli has is that he has no idea how to appropriately show that he cares and wants comfort him and thus falls back on helping Emil with something he
knows Emil cares about in the hope that Emil will correctly realize that Lalli cares about him. Assuming Emil would be completely fine after his hair is fixed would, in my view as a problably-autistic, person be extremely unreasonable,the problem is that NTs tend to misinterpret a lot of what we do anyways so Lalli may have gotten yelled at for trying to comfort people quite a lot before and is thus desperate to seek what seems like the safest way to at least not upset the person further.
So the takeaway is that it's quite interesting what we both assumed?
You, as a NT (?) seeing Lalli as autistic thought that he assumed fixing his hair would fix everything.
I, as an autistic person (probably autistic, definitely having some autistic tendencies) assumed that he did it to show that he cares for Emil in general, maybe with a bit of an attempt at avoiding potential fallout if it wasn't appropriate (with, admittedly, forgetting that maybe putting your hand on their shoulder may be a better idea, but then, Emil is a weird foreigner to Lalli and forgetting obvious things is probably part of executive functioning difficulties...or is that just me being an idiot?).
Then again, maybe there's a deeper misunderstanding here as well?
When I try to cheer people up, I very much don't expect them to feel fine immediately, I know that's basically never how it works, but I
do want them to know that I'm here for them if they need someone and/or that they don't have to be miserable alone, that somebody at the very least cares about them.
If you go by the assumption that people immediately feel better then it obviously seems much more bizarre (though that assumption in and of itself seems bizarre to me).
Still, that kind of misunderstanding is what I'd use as further evidence that he's on the spectrum since that is basically exemplary of the language barrier one has to face when trying to communicate across neurotypes, in either direction.