Title: As alone as a little white church in the middle of the desert getting burned
Fandom: Avengers movieverse
Disclaimer: not my characters; title from Fall Out Boy
Warnings: AU during Winter Soldier; mentions of torture/death/brainwashing
Pairings: Steve/Bucky
Rating: PG
Wordcount: 2040
Point of view: third
Prompt: Bucky/Steve, Red string of fate, Steve doesn't recognise it
Okay, so we know that MCU Steve used to be colour-blind. It's inconvenient in a world where there are intangible strings connecting you to the most significant people in your life. Your romantic soul-mate, your best friend, your mentor, etc. And they're all different colours. But Steve can't even see that the string connecting him to his best friend is the red of romantic soul-mates. And Bucky doesn't consider that Steve just can't tell; just assumes that Steve doesn't want him as a lover, so he sticks with friendship. And Steve thinks that whatever the string is connecting him to Bucky is the best friend colour, so...
Then after the serum, Steve can see the world in colour! But he doesn't know where Bucky is. But... colour! Now, if only he actually knew which of these colours is red... Because no one actually bothers to teach him what the colours look like. The grass is green, right? (Except they happen to in a place where the grass is brown from not being watered.) The sky is blue? (Except it's sunset, so the sky is actually purple and yellow and pink and cloudy.)
So when Steve and Bucky are back together again, Steve is still in the dark, and so happy about finding his best friend that he doesn't even think about asking what colour their string is. Best friends, right? So that's [insert colour]. (Which becomes inconvenient when he thinks that someone's blood is the wrong colour, because that's the friendship colour, and true love is red, just like blood is red, and... oh.)
And then Bucky dies. Steve studies up on the colours, angsts, crashes his plane, wakes up seventy years later, and so on.
The Winter Soldier knows about the colours from conversations he's heard, and he knows that the star on his metal arm is red. Red is for true love. So why is this man with a shield connected to him with the red string of fate?
TL,DR: Colour-blind!Steve doesn't realise that the string connecting him to Bucky is red, and doesn't study up on the colours until after Bucky dies. Years later, the Winter Soldier sees a red string connecting him to his enemy.
He never loses color, though he does not know what they mean. Grass is green, the sky is blue, his left arm and hand are silver, the star on his silver shoulder and blood are both red, his skin is a pale peach save for the silver arm, he is always clothed in black. There are bands around his wrists, fine as hair, that are as red as blood, and they chain him to the technicians and the handlers and the ever-changing men who give the orders he must follow. There is one band, on his right wrist, that is not red - it is a blue so faded it barely has any color at all. He does not know what it means. He does not ask.