"I don't care. He killed my mom."
The cold accusation rang across the room. The three men were frozen in a horrible tableau. Steve stood defensively in front of Bucky, bruises on his face already healing. Tony's hand hovered over the gauntlet on his wrist, having begun to summon his suit. All three of them were panting slightly, the sound of heavy breaths filling the room. In the next moment Tony lunged forward, his blaster firing, while Steve rolled over the broken glass of the shattered table, shield in position to deflect the blast. Bucky leapt over him, arm slamming into Tony. The billionaire fell back, but to his human credit, recovered quickly, punching the former assassin with his gauntleted arm. Bucky punched back, slamming Tony into the ground. It went on like that; Tony hardly holding his ground against the two super soldiers.
"HEY!" They all froze. Fist raised, blaster glowing, shield prepared to slam down. Sy stood in the door way, eyes wide in horror.
"What in Hades is going on in here?" The nineteen year old demigod's expression was thunderous. Large wings trailed behind her, burned and damaged patches still apparent even nine months after the injury, a guitar tucked under one arm. She stepped into the room surveying the destruction. They were in one of SHIELD's many safehouses; somewhere deep in Eastern Europe. The Avengers had reformed in order to take down HYDRA. They'd been waging war on the terrorist organization ever since the uprising in DC in January, and had just successfully completed another mission. The secret Avenger's eyes widened as she spotted the miraculously undamaged tablet on the floor. She slowly bent down and picked it up, her eyes tracking the events on the screen.
The tablet had continued to play the video on loop, even after it had been dropped to the floor. Snow fell gently across the screen, peaceful, as bright headlights flashed in the distance. Her eyes were glued to the screen, even as the men looked away. They didn't need to look at it anymore to know what happened next. A car crash. The glint of a metal arm. A red star. Flashes of light as the gun fires. Dark empty eyes over a black mask as the assassin turned away from his victims.
Sy looked up from the screen, gripping the tablet so tightly her knuckled had turned white.
"What's this?" She asked quietly. None of the men were able to respond.
"Steve?" She asked, looking first to her brother. The first avenger looked away. Sy turned to her friend next.
"Tony?" The inventor refused to meet her gaze, training both his blackened eyes instead on the tablet she clutched in one hand.
"James?" She asked softly, finally turning to the newest Avenger.
"What is this?" The winter soldier looked up at her, dark eyes haunted.
"Me."
AN:
To clarify the timeline; this occurs about nine months after the events of The Olympian Soldier, and is about nine months before the Age of Ultron movie. Because it's before AoU only parts of Civil War happen now, and there are no real sides because the fight isn't about the Sokovia accords; but over Bucky's role is the death of Tony's parents.
There is no way Bucky works with the Avengers for any real length of time without his past as the Winter Soldier coming up, so they have to deal with the fact that HYDRA made him kill the Starks. Even without the Accords or Zemo, Tony would have found out eventually and that would effect the whole team.
This is also going to solve some continuity issues for AoU, and in the rest of The Secret Avenger series because Loki's Scepter (and the mind stone) has been safe on Olympus since the Chitauri Invasion.