be on somebody's side

be on (one's) side

To be supportive or in aid of one or one's idea, plan, intention, etc. We're all on your side, Jerry; we just want to see this issue resolved as quickly and easily as possible. If that stellar legal team is on her side, then there's a chance she might actually win this case.
See also: on, side

be on somebody’s ˈside

support and agree with somebody: I’m definitely on your side in this.Whose side are you on anyway?
See also: on, side