qu'est-il advenu de

what became of

→ que
phrase Rare #44,337
what became of A formal or literary way to ask what happened to someone or something, or what became of them. The inverted word order is used in questions.
FR: Qu'est-il advenu de votre ancien professeur ?
EN: What became of your former teacher?

Et qu'est-il advenu de votre conversation?

And what became of your conversation?

— Les Fraises sauvages (1957)

Qu'est-il advenu de lui, depuis lors?

What became of him since then?

Qu'est-il advenu de lui?

What happened to him?

— Le Hobbit : Un voyage inattendu (2012)

Qu'est-il advenu de ton chien?

What happened to your dog?