KK fucking HATED Qiu when he first met them, but slowly starts developing a crush and eventually realizes that (also in Wheels, actually). They get really close but are way too scared to define their relationship as anything beyond best friends by the time they're fourteen. They get even closer when they're fourteen, because that's when KK comes out as trans and they can bond over that. They're super dependant on each other and they will develop beyond that I hope. What happens next depends on the rest of the game but they're in love.
KK and Tamarack became fast friends, and though KK loves Tamarack, their friendship never got as close as his and Qiu's. They start getting into more disagreements by the time they're teenagers, but they never stop being friends.