Bucky couldn't understand how the others had become so trusting of Y/N now. The assassin had tried to blow them all up, hunted Natasha down to kill her, tried to shoot Yelena, beat Nat into a bloody mess and had lied on the mission, faking their own death. Everyone seemed to have let that slide but Bucky couldn't shake the feeling that Y/N was up to something, playing some kind of game with them all.
He looked up at the apartment building across the street from where he stood, a light finally came on in the top apartment. Bucky kept watching until he saw the outline of Y/N appear in front of the windows, it looked like they were on the phone to someone. He needed to know what Y/N was doing, so he could convince the others, especially Natasha that they should be locked back up on the Raft and forgotten about.
Crossing the street Bucky made his way into the apartment building, slipping through the foyer door as another resident left, to busy on their phone to notice him getting inside before the door closed. He took the stairs and a few moments later he moved quietly down the corridor that led to Y/N's apartment.
Bucky made quick work of the lock on the sliding door that would lead inside, he opened it just enough that he was able to hear Y/N talking on the phone. They were so wrapped up in the conversation that they hadn't noticed the movement at the door. Bucky pulled a small recording device out and pressed the one button as he slipped inside, pressing himself against one of the walls that was in the shadows.
"She won't ever see it coming that is the whole point. The plan still works, we'll just have to adjust some parts of it that's all. I'm not going to lose the chance to kill her again" Y/N spoke into the phone as they paced around the apartment, "No I know it's not ideal but it's the way things are. Keep me updated on your end. They don't suspect anything and as far as I'm concerned they won't."
Rage rippled through Bucky as he listened, this had been exactly what he'd feared. Y/N was still the same fucked up psychopath he'd encountered in that boardroom at Stark Tower. They were just playing some elaborate part to make everyone else think they'd changed, that they were sorry and that they loved Natasha.
"Look I've got a couple of days to figure this out. Do you think you can get here by tomorrow night?" Y/N stopped pacing and leant against the wall, looking out the window, their back to where Bucky was currently standing.
Bucky clenched his jaw, glaring at the back of Y/N as he reached for the knife strapped to his thigh and pulled it out. The tip of the blade caught the light and it reflected in the glass of the window, it was the only warning Y/N had but it didn't give them enough time as Bucky rushed toward them. He slammed Y/N with all his strength into the wall, causing the bare brick to crack with the impact.
Cursing, Y/N threw an arm up just in time to catch the edge of the knife that was aimed for their throat. It bit into the exposed flesh of their arm, a thin line of blood appearing as Bucky pulled the knife back.
"What the hell are you doing?!" Y/N yelled at him as they managed to push Bucky back.
"You think you've got everyone fooled don't you? Not me Y/N, I know that you are just playing some twisted game and plan to complete your 'mission' to kill Nat. You can try and deny it but I heard and recorded everything you just said" Bucky snarled at her.
Y/N shook their head in disbelief, of course Bucky was looking to find any way to get them out of the picture. He was still holding on to the delusion that he and Nat were going to be together. Watching the way he flicked the knife in his hand, Y/N knew there was going to be no way to talk sense into him. So if it was a fight that he wanted then he could have it.
"Fine let's have it your way then Bucky" Y/N smirked darkly as they stepped forward, flexing their muscles, prepared to make him regret being such a damn arsehole.
Y/N moved swiftly and struck Bucky with a combination of punches and kicks, forcing him backwards. They both fought with brutal efficiency, striking each other with no hesitations, just like they had been trained to do. Y/N crashed into Bucky, but he had been expecting the move and used Y/N's momentum against them as they grabbed their arm and flipped them over, slamming through the glass coffee table in the centre of the room.
Letting out a grunt of pain, Y/N narrowly avoided the knife that Bucky was bringing down toward them. Picking up a handful of the broken glass, Y/N twisted and threw it into Bucky's face. I brought them enough time to get back onto their feet.
"I'm bored of this now" Y/N growled at Bucky as flames wrapped around their fists, their eyes filling with pure hate as they looked at him.
Bucky didn't back down as he watched Y/N summon their power. Instead he just flexed his vibranium arm and made his way toward them, he didn't care what Y/n thought they were capable of, he could take it.
**
Steve walked into the gun range and found Nat, Yelena, Clint and Wanda all in there. The four of them looked to be engaged in some sort of competition and from a glance at the targets, Steve wasn't surprised to see that Clint was the one winning.
"Have any of you seen Bucky? I've searched the compound and tried his mobile but no luck" Steve asked them as Yelena stepped up to take a shot.
Clint looked up from where he was sat with various different trick arrows laid out on a table in front of him.
"Last time I saw him was earlier when were all in the communal area" Clint replied as he set down one of the arrows carefully.
Natasha stopped loading her gun, a sinking feeling in her stomach as she realised when Clint had last seen Bucky. That had been when her and Y/N had gone past, when they'd had their conversation in the foyer.
"Nobody has seen him since Y/N left the compound?" Nat asked, the question had Yelena stop from taking her shot as she looked round at her sister and then to Wanda who looked equally concerned.
All of them had the same realisation then.
"Damn it" Steve shook his head, how could Bucky be this stupid.
"We need to get to Y/N's apartment right now" Nat said as she holstered her gun.
Nobody disagreed as they all headed out of the range together.
**
Y/N smirked as they dodged a punch from Bucky, they twisted around him and slammed their flame covered arm into his back, causing him to stagger forward. Capitalising on the advantage, Y/N stepped to the side and with both their flame wrapped hands grabbed hold of his vibranium arm.
"Really hope you aren't too fond of this arm" Y/N said as they concentrated all of the heat of their power through their hands gripping Bucky's arms, watching as the vibranium began to glow orange.
Bucky's eyes went wide as he saw the vibranium of his arm begin to wrap under the extreme heat and pressure of Y/N's grip. He dropped down onto one knee, trying to twist his arm free of Y/N but they matched his strength.
Looking around, Bucky spotted a large shard of glass from the coffee table just in front of him. Clenching his jaw, Bucky strained against Y/N's grip managing to move just enough that his other arm was able to grab piece of glass. Moving himself round, Bucky buried the glass deep into Y/N's thigh, twisting it, causing Y/N to let out a cry of pain and release his vibranium arm.
With his arm free, Bucky got back up onto his feet and watched as Y/N stumbled backwards, blood pouring from their leg. Their flames flickered out as they moved their hands down to their wounded leg trying to stem the bleeding.
"I'm not going to let you get anywhere near Natasha ever again" Bucky growled at them as he closed in.
"Fuck you Bucky Barnes!" Y/N spat as they looked up from the glass in their leg.
Bucky didn't reply as he grabbed hold of Y/N and drew back his vibranium arm, he slammed it into their stomach, causing Y/N to double over. As they did, Bucky punched them in the side of the head, sending Y/N sprawling to the ground.
He stood over them, glaring spitefully at them, ready to hit them again.
"What the hell are you doing Bucky?! Stop it now!" Steve came rushing into the apartment and launched his shield into Bucky knocking him away from Y/N.
Nat, Wanda and Yelena all followed Steve into the flat. All of them taking in the absolute carnage, the place was completely wrecked from the fighting between Bucky and Y/N.
"They're up to something, I heard them on the phone. They are going to still try and kill Nat" Bucky shouted at the four of them as he watched Nat and Wanda rush over to Y/N, whilst Yelena kept her gun trained on him.
"I don't believe you. This has gone to far Bucky" Nat shook her head as she cradled Y/N carefully in her arms, whilst Wanda assessed the wound on Y/N's leg.
Bucky pulled the recording device from his pocket and hit play.
"Well maybe this will make you realise that Y/N has been manipulating your feelings for them just to get closer to you" Bucky argued as he looked between them all.
They all fell silent as they listened to the recording.