WARNING: Major spoilers for Endgame, and some for other MCU films.
This is what I would like to believe what was going on inside Bucky's head during THAT scene of Avengers Endgame.
He saw it coming, years before he recognized the old man seated on that bench.
Bucky knew it but didn't want to acknowledge it then.
Could he really do that?
He wonders as he ignores Sam's panicked voice behind him.
"Get him back! Do something!"
Bruce stumbles on the controls while Sam was looking for any physical damage on the machine.
"Five seconds! You said five seconds!" Sam yells.
"I-I think he purposely stayed in the past."
Their voices start to fade as Bucky tries to process all of it.
If he really did it then that would mean…
Bucky never believed in magic or time travel, and after meeting everyone with all the crazy new powers and all the information flooding in, he could only understand a few.
He is trying to accept these things, but it is going to take him a while.
All he wanted was to focus on the normal, the mundane, the new peace that he was trying to find since he got all his memories back.
He was supposed to deal with the weird later, but it is now seated in front of him.
Earlier, when Steve was preparing for his mission to bring back all those magical stones that helped them to each of its respective timelines, Bucky asked Bruce about the consequences of the time traveling that Steve was about to do.
Bucky only understood the part about nothing in the past will affect whatever is happening currently, only a possible new reality created from the new events that would happen.
I get it, but at the same time, I don't.
Discussing the past made him think about the old Steve.
The original, that tiny Steve that he grew up with.
He remembers that Steve sketching on a stack of old newspapers.
Bucky saw the newspapers lying on the dirty street and he immediately took it, knowing full well that it would help Steve get his mind off from grief.
"Where do you get these ideas?" Bucky asked as he sat beside Steve's small crouched form.
"Images from my head," Steve said.
"Images from your head, huh?"
"Yup."
"You're good, but I don't get them."
"You always don't."
The machine in front of Bucky now is a real thing and far away from the images that Steve used to draw.
Far away from the imaginary. This is real.
Bucky's mind slowly shifted to the memory of Steve sketching on a new sketchbook from Peggy.
Steve was then the new super soldier that he cannot comprehend.
It was the day Bucky fell off the train.
"I keep thinking of better design additions for my uniform. Do you think Howard won't mind?"
"We have a train to catch."
"Don't worry, we will catch it."
The last thing he remembers from that day was the image of Steve's horrified face while screaming his name.
"Bucky?" Steve was looking curiously at him now.
"Be careful on your mission."
"You know I will."
Bucky leans in for a hug and Steve hugs him back.
"Don't do anything stupid until I get back."
Bucky smiles, remembering that he was the one who said that before. "How can I? You're taking all the stupid with you."
It is really stupid.
Feels stupid.
Because he still doesn't understand how it works.
How nothing can be changed.
Last time they exchanged those words, Steve was changed into someone he couldn't recognize.
Visually.
But it is still Steve.
He wonders, what is going to change now.
Since he got all his memories back, all he wanted was to undo everything that the Winter Soldier did.
What he did.
He wanted to go back in time.
Change everything.
Now that he found out that time travel is real but nothing from his past can be undone, he couldn't take it.
It's a huge slap to his face.
Maybe not a slap on the face, but a gut-wrenching punch.
"Nothing can be changed."
Bruce's voice is clear in his head.
"Nothing."
Definitely stupid.
Steve is now in the middle of the platform.
"I'll see you on the other side."
There was this look on Steve's face.
Bucky recognized it.
It's the same look Steve had when he asked to be kept cryogenically frozen.
The look of regret?
Longing?
Determination?
Certainty?
It's something.
Bucky is trying to understand what he saw.
"Off to the quantum realm," Bruce says while pulling the lever.
And Steve was gone.
"How long is this mission?" Sam asks.
"About five seconds to us," Bruce replies.
Five?
It's that long?
"He'll be back in five…" Bruce starts the countdown.
Five…
Five Howling Commandos other than me and Steve.
Five of his fellow Avengers when Fury got Steve out of the ice.
Steve loves those two groups of his.
He loves being able to fight.
"I can do this all day."
It's his favorite line when trying to win a fight.
I don't think he's going to get over that line.
Or even fighting.
What's there to fight for now that Tony's gone and that the world is saved?
There's nothing here anymore, except for me, Sam, and the rest of his friends.
We're all safe now.
An image of the original Steve practicing how to punch plays in Bucky head.
"Four..."
Four years since Steve freed me from Hydra's clutches.
Bruce told me five years had passed when Sam and I were gone because of that purple alien, so that makes it nine years.
But it's only four for me.
"Who the hell is Bucky?"
Four years of watching Steve's face filled with determination.
The determination to save me.
To save someone from his past.
To save everyone he can.
He would do anything to save everyone.
Anything.
"Thank you, Buck, but I can get by on my own."
Bucky searches for the memory of the first time he saw Steve as a super soldier.
"Three…"
"You pulled me from the river, why?"
"I don't know."
Three words that Steve refused to accept.
Steve badly wanted to make sure I was remembering him.
Look where it got us then.
There was three of us when I was awakened.
"You can't read that in a museum."
"Just like that, we're supposed to be cool?"
Steve didn't look at Sam.
He just had that look.
The happy look of finding that connection.
That connection from the past.
There was also three of us when that "Doctor" played that video.
Steve did everything to save me then.
To save what he believes in.
"It wasn't him!"
Bucky could never erase the memory of Steve dropping that shield.
"Two…"
That blonde lady just kissed Steve.
She's the second lady that I saw looking attractively like that at him.
How many other women are there Steve?
You haven't told me yet.
That's unfair because you've memorized all of my romantic endeavors.
"She's got to be a hundred years old by now."
"So are we, pal."
In the two times that Bucky saw Steve being that close with a woman, Steve had a different smile.
Bucky likes that smile.
"One!"
You keep talking about that one dance you missed.
You always do, Steve.
It would always take a while before you'd notice.
"I'm with you, I'm with you 'til the end of the line."
It was at that moment when thousands of images came flooding in.
Images of Steve.
"And he's back!" Bruce looks up.
The platform is still empty.
Sam looks scared.
"He's supposed to be back by now."
Bruce was confused.
Sam started to panic.
But Bucky immediately understood.
Steve stayed in the past.
Of course, he did.
He knew Steve would stay if given a chance to go back.
He saw it coming.
What a stupid thing to do when you can't change anything.
This is stupid, Steve.
Definitely Stupid.
Bucky gets it.
But at the same time, he doesn't.
He looks away from the other two men.
Really stupid.
He was supposed to deal with all the stupid things later, but the stupid is now seated on a bench in front of the lake near him.
Wait.
Is that?
Bucky would recognize Steve from any angle.
He did it.
Even from far away.
All of Steve's images in his head made that possible, even with all the changes.
If he did, did he do something to change the past?
My past?
Bucky waited for changes in himself.
Changes in the things he remembers.
Did he change anything at all?
He tries to dig in his mind.
Nothing came.
Same memories, same images, same sins, same pain.
Nothing else.
He doesn't understand.
But he tries to.
This time traveling thing is confusing.
What does it all mean?
Bucky did not want to go there anymore.
This is him, this current him, is inevitable.
If that is the correct way to understand all of this.
If Bruce is right, then there are other realities or universes, whatever the right term is, of him created out there and was free from all the pain he had to endure.
There's a Bucky out there who was saved by a time-traveling Steve from being a human weapon.
A Bucky who wasn't the Winter Soldier.
Who never killed Tony's parents.
Who killed no one.
Is that supposed to be it?
But it is all too confusing to Bucky.
Because an old Steve is sitting in front of him.
Not his small friend.
Not the fellow soldier in the war.
Not the one who saved him from Hydra.
Just an old man that is Steve Rogers.
But he is also the same one from earlier?
Bucky couldn't take it anymore.
He believes Steve did something.
Something in the past that still can't undo his present.
This present.
He knows Steve is not the kind who would let all these bad things happen to him.
Everything is inevitable, even if you did something.
How could that happen?
He would never get it.
Everything about it sounds stupid.
Feels stupid.
"Hey…" Bucky mumbles, trying to get Sam's attention.
Sam was still angrily inspecting the machine.
"Sam…" a little louder this time.
"What?!" Sam finally looked his way.
Bucky didn't look at him, so Sam followed his gaze.
He could see Sam's confused face from his peripheral vision.
"I…" Sam starts.
"Go ahead," Bucky whispered as he continues to stare at the old man's back.
He could see Sam was trying to urge him to go first.
Bucky just stood there.
Sam seemed to understand why, so he went to the bench.
Steve's back stayed facing him even when Sam sat down.
He didn't seem to bother checking out on Bucky.
But that's all right for Bucky.
Because now he understood the look Steve gave him before he left.
It was a look of contentment.
Assurance.
With a little bit of determination.
That was the end of their line.
Bucky is safe.
Saved.
In a weird confusing way.
That image of Steve is the last one facing Bucky.
He didn't want to see Steve's old man face.
He didn't need any new images of Steve's face in his memories.
How can I? This one definitely brought all the stupid with him.
I included a few of my headcanons in there because I feel like they fit well to the narrative that I was trying to do.
I wrote this because I badly needed an explanation as to why Bucky didn't greet Old Man Cap. Plus details in that scene is the part of Avengers Endgame that I am trying to comprehend, so I tried to write my thoughts in Bucky's perspective. [Coz Bucky is always confused as hell, but still going for it when he must, just like me as an audience.]