на сторону

on someone’s side

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phrase Rare #48,108
on someone’s side Usually used with встать (to take someone’s side), followed by the person or group being supported.
RU: Она встала на сторону брата.
EN: She took her brother’s side.

Понятно, вы встали на сторону де Винтера.

It's clear that you took de Winter's side.

— Ребекка (1940)

Я встал на сторону Тому.

I took Tom's side.

Том вечно встаёт на сторону Мэри.

Tom always takes Mary's side.

Том встал на сторону матери.

Tom sided with his mother.