Questions everyone had since Kai'Sa's role was released (and I'll try to come up with answers)
A lot of this is just speculation on my end since I was basing it on other medias about parasites-that-stick-to-people-and-grant-them-superpowers. I haven't read any rioter that came forward and gave us an explanation as well.
Also I'm going by the assumption you have already read her short comic, lore, and short story.
#Why/How Did Kai'Sa Survive the Rupture? This is entirely debatable since her whole village was swallowed and no one survived, but it may have something to do with her being the one to set the sacrifice lambs free. In return the void spared her to be the last or at least placed her in the tunnels somewhere further away from the rest of the villagers who were massacred as there were no purple light (signs of void life) in her area.
#Why did the voidling bonded with her? It may be because she came into contact with it at the time of it's death. Naturally, void creatures will attempt to attach itself to any biomass they can find (trees, animals, people, etc) but since Kai'Sa killed it while it was in contact with her. She halted it's subjugation and in the process Kai'Sa became it's mind and caused it to be reliant on her to survive. In other words she "absorbed" a carcass of a voidling. Any parasite know full well that once their host dies so will they, so once they are bonded it has to do whatever it can to keep Kai'Sa alive.
#How did a 10 year old girl survive in the Void Tunnels for 10 years without food or any prior survival skills? Well firstly, as seen in Kaisa: breach the parasite is able to convert void energy that is present in other void creatures as food for the host which in turn, the parasite draws its power from.
Secondly, from the same comic Kai'Sa kept on referring to the Void's Eco-System as having a pattern that she was able to see. While in that 10 year time skip it may have just been experience that taught her, the parasite can provide genetic memory on how the creatures behave to the host so that she is able to get around them better.
And third, the village that she lived in was a hunting colony of sorts so generally everyone was taught how to survive on their own if it comes to that. It came up in my head when her story introduces a second hunting village with the same sacrificial practice that Kai'Sa's village had.
#The other two humans in league that has ever been to the void and came back had gone insane, how come Kai'Sa is completely fine mentally and physically? The area that the village was dragged down into were the void tunnels. They are more so an extension of the Void (similarly to the upside-down tunnels in Stranger Things) than the actual Void dimension that caused Malzahar and Kassadin to go insane as they were unable to comprehend it. Which would explain why she didn't.
Physically, she is superior to a well trained athlete because the hard-as-steel-carapace had fused with most of her body down to the nervous system (that is how she is able to control the pods on her shoulders) granting her spider-man level abilities. If she was to lose a limb or suffer injuries it would just grow back eventually.
Mentally, Kai'Sa is still sane. Though is unable to show empathy or express her feelings because of the isolation (she still has feels tho). Which is why her VOs are really bland and are somewhat childish because in the right mind she still isn't any different than the girl who fell inside a hole away from civilisation 10 years ago.
And that's about all I can think of, most of the stuff I come up from having read and watched Venom, Spawn, Stranger Things, and Resident Evil.
