Niki had a very strong urge to kick her in the shin. He didn't, but he thought about it, quite a bit. It would feel good to kick her. But then she might try and hex him or something else unpleasant. And so he decided not to.
"You should be. Nice to me," he said. Not that he was nice to everyone, but that was different because that was him! He thought everyone should be nice to him.
Niki twisted up his face in another scowl just for her, before he stepped by her and then stalked across the park.