The passive form and passive sentences, including the “suffering” passive.
書く→書かれる, 食べる→食べられる, する→される, 来る→来られる. The doer takes に.
わたしは ははに しかられました。
I was scolded by my mother.
Group I: あ-row + れる (書く→書かれる, 読む→読まれる). Group II: ます-stem + られる (食べる→食べられる). Irregular: する→される, 来る→来られる. The agent is marked with に.
The subject is affected by N2's action — often something unwelcome.
（わたしは）おとうとに ケーキを たべられました。
My little brother ate my cake (on me).
Japanese often uses the passive to show the subject was adversely affected (the “suffering passive”). The agent takes に, and what was acted on can stay marked with を.