The Winter Soldier's Last Kill

This is based on a tumbler prompt by: rogersbarnes
Au where the winter soldier ends up killing steve on the helicarrier, and the moment he breaks steve's neck is the moment he reminds hearing those same bones breaking after a small boy with blond hair and blue eyes tried to climb a tree - so i can see the world from up high Bucky - and fell and the other boy thought that the sound of his bones cracking was the worst possible sound that he could ever imagine, but then the blond boy started screaming and he knew he was wrong, that nothing could be worse than that. but the winter soldier - no no no no what have i done im sorry steve i remember you now please - was wrong yet again - no steve i remember you now please - because nothing - steve please wake up - absolutely no sound - come back to me steve please, i didn't mean it, i didn't know steve please - is worst then silence - steve...