have got back
have (got) (someone's) back
To be willing and prepared to help or defend someone; to look out for someone in case they need assistance. Don't worry about those thugs, buddy. I've got your back if they ever come bother you again. You can always rely on your parents to have your back.
have got (someone's) back
To be prepared or ready to support or vouch for someone, as in a crisis.