Is or are after Plural noun? Tantrums is or are?

Hello teachers,

I have a subject-verb agreement question. Sometimes we say "This isn't you" or "This is just not you" to mean that a particular trait is not usually associated with a person. If I want to mean that a person usually doesn't throw tantrums, what would be the grammatically correct way to say it?

Tantrums isn't you.
Tantrums aren't you.

Could you please help?