Babydoll (Bucky Barnes x OFC Maximoff (Babyd...
Amalia 'Mali' is the older sister of Wanda and Pietro Maximoff, she underwent the same experiments and became enhanced just like them. Seeing promise in the older sibling Strucker sent Amalia to receive more training. Separating her from her younger siblings. She was sent to one of the last surviving Hydra bases, that only a handful of agents knew about, there they trained her up as an assassin, using her new abilities she became unstoppable. Eight years later, the twins are now fighting WITH the Avengers and Amalia is still with Hydra, believing her siblings had been murdered at the hands of the heroes. Her anger can be both powerful and vengeful.
Bucky Barnes worked a few times with Babydoll whilst he himself was with Hydra, so when they try to bring her out of the dark and into the light, he sees to it himself that she can be rehabilitated.
Book Three of the Avenger soulmate books - Bucky Barnes