The leash

What the oath actually is

Maeve founds the Cadre after the second Valg war, binding the strongest Fae warriors alive to herself by blood oath. In Doranelle it is spoken of as the highest honour available to a warrior. It compels. Not persuades — compels. Everything the six of them do across five books is shaped by the fact that when she gives an order, the body obeys before the man decides anything. The series spends its whole length taking that apart.

How Rowan got in, and out

Lorcan Salvaterre finds him after Lyria dies — grief-hollowed, wandering, self-destructive — and recruits him. That is what the Cadre is for: it collects men with nothing left to lose and gives them somewhere to put it. Rowan is also the only one who is ever released with honour, so he can swear to Aelin instead. Canon is explicit that it is the single recorded case. Everyone else leaves by being torn out, or by dying, or by breaking something that was not supposed to break.

Eyllwe

At the Stone Marshes, Lorcan signals Maeve — believing she is the only force that can beat Erawan — and it costs everything. Maeve compels Gavriel and Fenrys to attack him. Elide is mauled in it. Aelin is taken. Afterwards Maeve strips Gavriel and Lorcan of their oaths without honour, which is the opposite of what she did for Rowan and is meant to be understood as such: the oath was never a bond, it was a collar, and she can unbuckle it as an insult whenever she likes.

Connall, and what Fenrys did

She uses the oath to make Fenrys's twin brother Connall drive a dagger into his own heart, with Fenrys forced to watch and unable to move. It is the most explicit statement the books make about what she has actually built. Later, held in wolf form and compelled to watch Cairn torture the captive Aelin, Fenrys fights the oath itself — and breaks it. The unbreakable one. He re-swears to Aelin afterwards, by choice, which is the whole argument of the thing.

How it ends

Gavriel dies at the gates of Orynth, holding them for the son he had only just been allowed to stand beside. Maeve is killed by Aelin and her court, and her death dissolves the last binding — freeing Vaughan, who had been held longest and quietest of all of them. Six warriors, and not one of them ends the series still wearing it.