I had a devilish idea for a side scene of Xerneas. It would be that when they have sex and the MC gets just before cuming she stops and lets him settle down a bit before resuming and edges him again repeatedly until finally lets him cum into her but unlike the usual amount it would be 10 times more cum being shot out and since she can heal faster than being damaged she would have a mountain size belly that would make Mew drool and demand that done to her. Xerneas would be so used to pleasure from being horny 24/7 that she would not get lost in the pleasure easily.