bratricidal 

The want or verb to end the life of one’s own brother.

I’m feeling very bratricidal.

bratricidal by VampyrGames November 13, 2023

Fratricidal war 

It means when one is killing their own family or society members of the same group.

Brothers killing each other for the throne led to fratricidal war.

Fratricidal war by AZRAEL34 March 7, 2022