A little over a year ago, I adopted a female kitten. But she had (and still has) endless supply of energy. I once spent like 1.5 hours playing with her to tire her out and in the end I was the one to tire out. So adopted another female kitten 1 month younger. After the standard introduction, they got along fairly well. But even to this day the older one likes to bully the younger one whenever she’s in the mood. After the bullying session (with comical yells for help) end, they’d often sleep right next to each other.