who are you and what have you done with someone

colloquial rhetoric

(colloquial, rhetorical question) Said to express surprise due to a perceived drastic change of behaviour of a person.

Japanese Meaning

（口語的な表現）相手の態度や行動が劇的に変わった場合に、驚きを込めて『あなたは一体誰なの？どうなってしまったの？』と問う意味合いです。

気難しい兄が急にみんなを褒め始めたとき、つい「一体誰になったの？私と一緒に育ったあの人に何をしたの？」と言ってしまった。

Sense（1）

(colloquial, rhetorical question) Said to express surprise due to a perceived drastic change of behaviour of a person.

Who are you and what have you done with the "real" editors of The Roanoke Times?

who are you and what have you done with

（ canonical ）

someone

（ alternative ）