It's not even about canon Bucky it's about the things fanfic writers extrapolated upon that are so tantalizingly visible in the canon after you examine from that lens
using a character who is so physically powerful and dominating to explore the horror of bodily violation and lacking bodily autonomy is so peak and digs into a place of fear and dread and nastiness that is really crisp and unique and rich
there is the horror of being physically transformed into arguably a kind of undead creature, part human and part machine, having his body repaired, maintained, monitored, examined, probed, cut open, modified, experimented on...
the way he stops being a person to his technicians and his handlers, the way he's a weapon that is constructed out of metal and flesh, the way his body isn't his, because his body was salvaged, reconstructed, and repaired so that it could be used
the way he is hollowed out, memory and identity and independent thought burned out of him, until he is just a completely passive thing that is used.
all he knows is that his body is for others to use. he is strapped to an operating table, chained in a windowless basement, curled up in a mildewed cell, kneeling at his handlers' feet, cuffed and restrained in the Chair, every experience reinforces it, he is their weapon and their tool and their lab rat and their tinkering project and their plaything
he is an implacable monster, a thing of dread, a hypercompetent war machine who rips apart cars with his hands and slaughters people effortlessly, with a smooth apex-predator strut that projects pure power, control, and efficacy, and he is powerless and confused and scared
and his lethality is used as an excuse to deny his humanity further, to restrain him and use pain and degradation to control him, because that's the only thing he understands, right?
I am so, so, so, so, so normal about him. The Bucky
