z.a.t.o spoilers. thoughts on tosya
tosya appeared and then disappeared before asya properly got to know vadim, ira and marina. ira and vadim are her classmates but from what we gather throughout the game - asya was always very secluded and barely knows anyone. vadim was picking on her for a long time, but she only sees his other, caring, human side during the game, so 3 years after tosya's vanishing. we also witness her fully fall for ira at the same time, tho there probably was sympathy before too. and she didn't know marina at all before ira's disappearance.
so if at the end we see tosya's image as a mishmash of all three, then she would've looked differently when she first was created by asya?
at the end, when asya is the only person left in vorkuta-5, she starts to lose her memory, forgets some past events and even vadim and marina's names. it's only natural that she'll forget how tosya looks (and maybe behaves?) too. maybe she used their traits to fill the gaps that formed in her memory of tosya? so asya could imagine and "bring to life" her at all.
when asya describes ira to tosya (she only remembers ira's name to the very end i'm gonna cry-) she says that they are very similar. for some reason even tho tosya has all three's external features, her personality is akin specifically to ira's. this might be for two reasons:
asya liked ira (at least partially) because of her similarities to the dear friend she lost. she lost tosya's support, her confidence that asya herself lacks, someone to hold onto in the world so alien and hostile. and here ira steps up for her - support asya lost and desperately needs.
asya barely remembers tosya at this point and she needs to fill in the gaps in her personality too. so of course she turns to someone she loves - ira. asya also misses ira very much, and her traits in tosya probably make asya feel like she meets her once more.
