I need help! please, my girl kitten is going crazy!

Question
My question is, that I just got my boy kitten fixed.. The girl kitten now doesn't respond to his smell now and hisses and tries to attack him. Their brother and sister so I don't understand why she's not realizing that's "her" brother!! The boy kitten doesn't understand why she won't play with him? And I feel so terribly bad for him, he will go to play with the girl and she tries to hurt him. Please help! I want to understand how I can help my kittens!! Please.

Answer
Marissa,

This is not uncommon.  Cats know each other mostly by scent.  After being at the vets office and under anaesthetic, your boy kitten does not smell "right". After a few days, things should return to normal, when his scent returns to normal.

Best regards.. Norm.