Something that always puzzled me was how Lalli went from
When first meeting Emil, to
On the military train. But rereading the comic, I think I understand a little better now.
Originally, Lalli is hesitant at the idea of working with someone else. He isn't used to being around people, and he finds them confusing enough as is, without an added language barrier. But unlike what I initially thought, he isn't completely opposed to it. He doesnt mind working with Emil, as long as he still gets to do his own thing, and as long as Emil isn't a "weird person."
We don't really know what Lalli considers to be "weird", but I believe it's anything he doesn't understand, like Tuuri says later in the comic. Lalli is used to finding people confusing and incomprehensible, since he's not used to being around them (and likely on the autistic spectrum in some way). So what he considers to be "weird" is someone who he can't form any understanding with.
But Emil consistently tries to find an understanding with Lalli. Later on this same train journey, after seeing that Lalli ate his sausage, instead of getting annoyed, he gets more sausage. He tries to understand why Lalli took his sausage. Not because he wants to annoy Emil, but because he just likes sausage.
When his cousins are making Lalli uncomfortable, he sees that Lalli doesn't like it and stops them, instead of just ignoring it. He shows he's trying to understand Lalli by being receptive to how he's feeling.
And I think Lalli notices that Emil is trying to understand him, and appreciates it. So, going back to that moment on the train:
Really, this is just another small moment where the two try to find an understanding. Lalli knows Emil wants to be understood by him, and he's proved that he's willing to understand Lalli, so Lalli reciprocates by showing he understands Emil.
This is the basis for their relationship throughout the story. This is how they can form a friendship while not being able to verbally communicate. A two-sided attempt at understanding. When the two are on bad terms, it's because there's a lack of understanding caused by the language barrier, or their differing life experiences, or their failure at communicating. When they both work to understand the other, their relationship is at its best.
Thanks for reading and I hope you liked my analysis :)