Don't really know. But in the beta of genshin, the original Mc's Were Named Kate And Kevin Kaslana. And in the Twitter introduction post of the game, It is mysterious signed by "K.K"... It could be Kate And Kevin, Not exactly sure.
Easiest way to explain Kevin and Kiana relationship is Kevin Kaslana the last human in his era,He fall in love with genius girl who lead human fight honkai but due to genetic experiment make his body below 0 celcius so he can't even touch her,then before the girl died she give Kevin a artificial baby from their gen so human can still exist,Kiana is a clone created from latest Kaslana. This is honkai impact 3rd lore,Welt is actually from honkai impact 3rd universe then he move to HSR.
