My issue with surface level feminist readings of Buttercup in the Princess Bride is that they completely miss out on the fact that Buttercup, though unintentionally, ends up psychologically torturing Humperdinck throughout her captivity. She's a damsel in distress but she is actively laying the groundwork for her escape.
Initially, Humperdinck views Buttercup as a pawn - I kill her and claim assassination, I get to go to war. He hires Vizzini to abduct and murder Buttercup and frame Guilder for the death. But she escapes and he has to go hunt her down and subsequently finds out about Westley.
I don't know about you but if I had been abducted, held at knife point, believed I had been abducted again, had gotten the better of my new captor only to realize while he's rolling down the hill that it's actually my true love, not hesitated to yeet myself down after him, fell into quicksand and almost suffocated, got lit on fire, got attacked by a giant rat and escaped only to be captured again by Humperdinck, I'm not assuming I have room to negotiate for my man's life.
That's not only one of the first things Buttercup does after several attempts on her life in the span of a few days, she follows it up with telling Humperdinck she'd rather commit suicide than marry him. I can't think of another instance when a prisoner regularly goes to their captor and renegotiates their imprisonment.
You can say Humperdinck manipulated her into agreeing not to off herself by saying he'd send ships to Westley about how Buttercup still wants to marry him. However, the second she calls him out on his lie, that man loses his mind. He locks up Buttercup in her room, and goes to the pit to end Westley himself.
Westley is still being held and tortured in the pit by Rugen. Westley, logically, cannot in any way, shape, or form be considered a threat. But Buttercup's conviction that somehow she and Westley will reunite is too much for Humperdinck.
Note, Humperdinck doesn't need her to trust him, much less like him. Her faith should not factor into his plans AT ALL, but here he is, throwing the lever all the way up on the device because the threat of Westley's continued existence is enough to scare Humperdinck.
He believes Westley dead and still throws a tantrum over Buttercup telling him no, Westley will rescue her. AND THEN HE DOES!
Humperdinck has stacked the deck against this happening in every way he can conceive and still he's thwarted. Westley's still gets in despite 1) being as physically capable of doing anything as a stretch Armstrong, 2) having two other guys, a cloak, a torch, and a wheelbarrow as his assets to infiltrate a guarded castle, 3) said partners in crime leave him alone to handle their revenge side quest and in Fezzik's case, get their escape sorted out.
He watched Westley struggle to get upright to face him for a sword fight. He knows, logically, that this is a battle in his favor, but EVERYTHING Buttercup says would happen HAS! And she hasn't batted an eye at Westley standing on his own to face Humperdinck. She believes Westley will win, and deep down, Humperdinck does too. So he concedes, gets tied up by Buttercup and tries to regain some respect by saying he knew Westley was bluffing.
It doesn't matter that he knew Westley was bluffing, Buttercup wasn't. He lost a battle of wills to Buttercup. Her convictions and beliefs in the face of all odds was stronger, superior, to anything Humperdinck could muster up within.