So in her voice when she encounters Kassadin she would ask if that was her father. However in their biographies the timelines and the locations did not seem to match. Could anyone in the Kai'sa designing team tell me if Kassadin is Kai'sa's dad?
It's not confirmed. Anytime a dev responds on the matter, they don't give a hard "No,", they just give a tongue in cheek response like "Wait, really?" or "Wow, that WOULD be interesting".
I think it's pretty obvious that she is Kassadin's daughter, but that bit of info isn't just trivia. The loss of his daughter basically drove Kassadin insane and inspired his mission to fight the Void, by any means necessary. If it turned out that his daughter was alive this whole time, would everything he's sacrificed fighting the Void have been worth it? Is he even capable of living a normal life now? Discovering his daughter is a huge moment in Kassadin's story that can't just be confirmed offhandedly.
We're likely waiting for a short story or something along that line to confirm it.
It's not "officially confirmed" yet, but everyone knows that it's pretty obvious.
It's kind of like Yasuo and Riven's story before Confessions of a Broken Blade. Everyone knew Riven killed Yasuo's elder (now known as Elder Souma). Yasuo's lines made it obvious. The fact that they got Versus skins together made it even more obvious.
But it wasn't technically confirmed until Confessions of a Broken Blade. A big mystery it was. [zombie-brand-mindblown]
Kai'Sa being Kassadin's daughter, like the ever-unsolvable mystery of who killed Elder Souma, is a very big and important question that we couldn't possibly figure out until it's confirmed. [slayer-jinx-wink]
I spoke to their writer extensively about this around her launch, it isn't confirmed to be Kassadin because they have not yet met in the lore yet. its very well possible they are father daughter, but it isn't Riot official yet
