i've had to think about this a bit
honestly i think xu's idea of a mindblowingly pleasurable singularity would be something like the time she was alive but instead of heading off to japan she's lady yu's personal beloved retainer
i dont think xu would be super kinky but she would get a lot out of pretty women praising her and probably wouldn't mind a bit of degradation or feet licking either
the singularity would def center around lady yu but when chaldea goes to resolve it mash would fs be compatible with it lol
it's a bit tough for me to consider cuz i dont feel like xu's love for lady yu is necessarily sexual but i can totally imagine her getting turned on when she gets called a good girl and pat on the head by someone pretty lol