s'étaient

had

→ se
phrase Rare #38,360
had The third-person plural imperfect form of être with the reflexive pronoun se. It is used with a past participle to form the pluperfect for reflexive verbs, often translated with “had” in English.
FR: Elles s'étaient levées très tôt.
EN: They had gotten up very early.

S'étaient-ils trompés de dossier?

Had they gotten the wrong file?}

— Apocalypse Now (1979)

Ils devaient être en train de lire ou alors ils s'étaient endormis.

They must have been reading, or else they had fallen asleep.

— Die My Love (2025)

J'ai entendu dire que Tom et Marie s'étaient remis ensemble.

I heard that Tom and Marie had gotten back together.

Si elles s'étaient montrées, il leur aurait offert.

If they had shown up, he would have offered them something.

— Arrietty, le petit monde des chapardeurs (2010)

Les médecins ne s'étaient pas trompés.

The doctors had not been mistaken.

— Demain tout commence (2016)

Le temps et l'espace s'étaient évanouis.

Time and space had vanished.

— Tigre & Dragon (2000)