frère cadet
I've always wanted to meet your younger brother.
J’ai toujours voulu rencontrer ton petit frère.
Tom is your younger brother, isn't he?
Tom est ton petit frère, n’est-ce pas ?
Tom wasn't born in this hospital, but his younger brother was.
Tom n’est pas né dans cet hôpital, mais son petit frère, si.
He was mistaken for his younger brother.
On l’a pris pour son petit frère.
Your younger brother will keep an eye on you.
Ton petit frère veillera sur toi.
— City of God (2002)
I know you think of me as a younger brother, which is fine.
Je sais que tu me considères comme un petit frère, et ça me convient.
— Jojo Rabbit (2019)