KilluCro
These two have entered my mind and will not leave. They are so alike that they would hate eachother at first, but learn how to love both one another and themselves. Both of them were only ever supposed to be weapons, but they grow to become so much more than the killers their parents wanted them to be, because they are kind despite their circumstances. In spite of the hell they were forced to endure, they are gentle and loving. They rely on eachother to pull themselves out of their darkest depths, because everything is much scarrier in the dark.
Killua and Crona are inherent foils to one another--one wants nothing more than to abandon his family and leave his past behind, and the other can't help but cling to what little approval they were shown. Which is more natural? The need for comfort, or the self preservation to distance yourself from danger? Does it even matter to those who have been treated as anything but human for their entire lives? They do not believe in the good within themselves, but at the same time can't understand why the other doesn't see how great they truly are. Killua is brave, Crona is a coward. Killua is selfish, Crona is selfless. They make up for what the other lacks, balancing eachother out.
I think Killua would like high adrenaline dates like an amusement park or something at least a little dangerous, meanwhile Crona would prefer more mundane dates like a picnic or ordering takeout. Killua personally finds them boring at first, but slowly grows to appreciate the peacefullness and just getting to spend time with his lover. Crona would absolutely shit their pants the first time Killua takes them on one of his dates, but they learn how to like the rush of adrenaline when they're not actually fighting for their life and with someone by their side to lean on when things get to be too much.