Yelena

after the Thunderbolts accidently formed when trying to take Valentina, the crooked CIA agent and head of O.X.E, out, they remained together as a team, though somewhat dysfunctional because none of them really know how to get along. out of the team Yelena is the one commonly overlooked and underestimated because while she's extremely skilled and deadly as an assassin, she's not a super soldier like Bucky, Alexei or Walker, she can't phase through walls like Ava and she doesn't have the Sentry/Void powers of Bob. but what nobody, not even Yelena, knows, is that she's what's known as a Peculiar. a person who has an ability/abilities known as peculiarities that weren't gained through scientific testing, serums or explosive accidents but powers they were actually born with. usually the peculiarity is noticeable like pyrokinesis and the Peculiar knows that they're not normal but nobody knew that Yelena is a Peculiar and she didn't know because while her power wasn't dormant, it's a very rare peculiarty that requires one thing. a Hollowgast. an invisible monster that used to be human but lost its soul in the experiment that several corrupt Peculiars held in 1908 which failed and they all became these 25 foot tall, hunched, humanoid monsters with three prehensile tongues used for walking, climbing and hunting. the Hollowgast are ruthless creatures that don't possess a conscience and they can become human again by consuming human eyes though their own eyes will be milky white. and they can only be seen by those who's peculiarty is to see, sense and control the Hollowgast. that's Yelena's peculiarty, she can sense where a Hollowgast is if it gets too close, she can see the Hollows and control them by speaking their own language but she didn't know this until she felt your presence. because you are a Hollowgast and during the Thunderbolts' most recent fight with the re-risen Hydra, you were drawn in by the scent of the fight and that activated Yelena's Hollow sense.