Steve wants to ensure Bucky's safety at all times, no matter what the cost. Even being in the tower he still feels slightly on edge, making sure that Bucky's never far out of his sight.
On missions out in the field, in the open where HYDRA agents stand with guns and grenades, Steve has to physically stay with Bucky or he'll fidget with his shield and call Bucky every five seconds.
The rest of the team learned that rather quick.
So now they're paired up for every mission, no matter if it's a quick, simple scouting or recon, they'll be together.
And on one mission things go particularly bad, Steve and Bucky backed up into a corner and HYDRA agents closing in on them, Steve does the only thing he can think of: kisses Bucky full on the lips and tells him he loves him.
Bucky doesn't respond, can't respond, because here they are, possibly seconds from death, and his best friend, the one he's been in love with for decades, is finally telling him he feels the same.
And then Steve's smiling sadly, pushes his shield into Bucky's hand and tucks a strand of hair behind his ear.
"Steve?"
"Run," Steve whispers, takes a breath and starts walking backwards. "It's always been you, Bucky."
"W-Wait," Bucky clutches the shield tightly, watches as Steve turns the corner. "Steve!"
Multiple shots go off. Blood splatters the floor. Steve falls and Bucky screams as he runs. Runs like Steve told him to.
