If you have something against someone, you dislike them for a reason.

I've nothing against him - I just don't have much in common with him. 我一点都不讨厌他，只是和他没有太多相似之处。

She's a great singer. I don't know what Elton 's got against her.

I don't have anything against the police, but I expected them to do more.

I wish she would tell me to my face what she has against me.

They attacked his house repeatedly, but he never found out what they had against him.

See also: against (OPPOSING)