Here's the case for Sharon Carter being The Falcon & The Winter Soldier's Power Broker. Considering Falcon & The Winter Soldier's debut season is only 6 episodes long, the MCU series certainly has an abundance of villains. There's Karli Morgenthou and her Flag-Smashers, John Walker f.k.a. Captain America, the surprisingly charming Baron Zemo, and French super-grunt Georges Batroc. But lingering in the shadows is a fifth antagonist who has been named, but not yet revealed on-screen: the mysterious Power Broker.
Little has been revealed of the Power Broker's machinations and intentions thus far - only by reputation is the character known. Hunting for the source of the new super soldier serum, Sam Wilson and Bucky Barnes discover that the Power Broker is based in Madripoor, essentially acting as the don of Marvel's criminal underworld, which exists in perpetual fear of the villain's wrath. The Power Broker also funded Dr. Nagel's super soldier research, but the resulting samples were spirited away by the Flag-Smashers, who have been pursued by the Broker's goons ever since.
The true identity of the Power Broker remains unknown, and a multitude of options remain on the table. Like the Marvel comics, the Power Broker could be a totally new character, regardless of the smoke and mirrors. Given his wealth and influence, Zemo might've been the Power Broker, although how that lines up with the Baron's anti-superhero sentiments is anyone's guess. But by far the most popular theory is Emily VanCamp's Sharon Carter being the Power Broker. This former ally of Steve Rogers claims to have been exiled by the U.S. and is "laying low" in Madipoor but her story smells fishier than the Wilson family's boat.
The "Power Broker" Episode Title
The first hint as to Sharon Carter's double life is the name of the episode in which she returns. Falcon & The Winter Soldier episode 3 is simply called "Power Broker," which is strange considering the title character is only discussed in the vaguest possible terms, having minimal impact on the episode's plot. Episode 3 isn't even the first time the Power Broker is mentioned in Falcon & The Winter Soldier - the camera-shy villain is name-dropped by the Flag-Smashers in episode 2, while Karli and her followers escape goons sent from Madripoor, confirmed to be "the Power Broker's men." Marking Sharon Carter's comeback, the title of Falcon & The Winter Soldier's third episode would make far more sense if the Power Broker is Sharon herself.
Taking Down Selby
Speaking of Sharon Carter's reemergence in the MCU, her rescuing of Sam and Bucky is strangely convenient. Probing for information on the super soldier serum, Zemo leads his new friends to Selby, a Madripoor criminal and an associate of the Power Broker. The ruse is rumbled thanks to an ill-timed phone call from Sam's sister and, discovering she's being lied to, Selby yells "kill them" before immediately being shot by a hidden Sharon Carter. On the surface, it seems that Sharon saved her friends just in time - but why snipe Selby and leave her goons (the ones doing the actual punching) for Sam, Bucky and Zemo to deal with? An alternative interpretation of these events would be Sharon, as the "always watching" Power Broker, kept an eye on the Avengers' movements in Madripoor. When Selby issued the kill order, Sharon knew Falcon, the Winter Soldier and Baron Zemo would win, and Selby would inevitably be questioned by them. Sharon could've killed Selby to stop her leaking any details about the Power Broker.
Sharon's Civil War Punishment
When Captain America: Civil War kicked off, Sharon Carter, predictably, took the side of Steve Rogers. She risked her job to steal Steve's shield and Falcon's wings from governmental custody, returning each to their respective owners just in time for the fateful inter-Avenger battle. Since then, plenty of healing has transpired between the American authorities and the superheroes of Team Rogers. Wanda Maximoff became a free woman, Scott Lang got house arrest, Clint Barton is all clear, Bucky Barnes is in therapy, and Sam Wilson is working as a military contractor, while an entire section of the Smithsonian is now decided to Steve Rogers. As messy as the MCU's Civil War was, much of that animosity is water under the bridge.
Except for Sharon, who got exiled. Despite having no real role in the violence itself, and merely abetting Steve's cause instead of being directly involved, Sharon Carter is a wanted woman who cannot return home. Considering how Steve's other pals have been treated since Captain America: Civil War, Sharon's punishment doesn't fit her crime whatsoever. Could her sad story be a cover for Sharon's turn to villainy?
Sharon's Lavish Existence In Madripoor
A smart and capable SHIELD agent, there was never any question that Sharon would thrive under the lawless lights of Madripoor. Sure enough, Sharon makes a living dealing valuable works of stolen art and other goods exclusive to the black market but, once again, Sharon's tale doesn't quite line up to reality. Reappearing in Falcon & The Winter Soldier, Sharon has a chauffeur, guards, a massive house, and a wealth of influential contacts. While these funds certainly could've been raised shifting a few paintings, her lifestyle is more in-keeping with a mafia super-criminal than a black market hustler. If Sharon really were the go-between she claims to be, she'd surely be keeping a lower profile. Instead, Sharon gives the impression of a woman in complete control of her surroundings.
Sam & Bucky Notice Sharon's Change Of Character
Cut loose by the CIA, Sharon returns to the MCU with a far darker attitude. Describing patriotic superheroes as "bull***t," Sharon Carter has evidently lost faith in everything Steve Rogers stood for. If her status as America's Most Wanted is true, it's hardly surprising that Sharon has become more cynical - she helped Captain America, kissed his face off, and then hung out to dry while Steve went back in time to romance her great aunt. While Sharon's change of attitude may not be a shock, the turnaround does set up a potentially villainous career change for this once-wholesome character. Indeed, Sam and Bucky both notice the difference, with the latter describing Steve's ex as "kind of awful." Is Sharon really the grizzled vigilante Falcon & The Winter Soldier suggests? Or something much more sinister?
The Power Broker's CIA Connection
A subtle, but important, clue comes when Sam, Bucky, Zemo and Sharon finally catch up with Dr. Nagel inside his Bond-esque shipping container laboratory. Curiously, Sharon is the only member of the quartet to remain outside. With assassins on their tail, Sharon's guard duty proves very useful indeed, but it's possible that Nagel would've recognized her as the Power Broker if she went inside, blowing her big secret to Sam Wilson and the others.
Furthermore, Nagel claims to have previously been employed by the CIA, attempting to recreate the classic super soldier serum formula. After the Blip, only the Power Broker was willing to fund the continuation of Nagel's research, but how would the arch-criminal of Madripoor know about Nagel's top-secret activities unless they already possessed connections to the CIA? Sharon Carter might've known about Nagel for years, and courted his expertise after turning to evil.
Sharon Doesn't Use An iPhone
A weird detail, but bear with us on this one. As explained by Rian Johnson (courtesy of Nerdist), Apple are more than happy for film and TV characters to be seen holding their iPhones, but insist upon a rule whereby only protagonists or neutral characters can own them. The technology company clearly has an issue with their products falling into the hands of villains, believing that audiences would be less inclined to part with their hard-earned cash if they witnessed Thanos giving orders to Corvus Glaive over Facetime. The MCU usually loves a good iPhone (Steve Rogers certainly did in Captain America: The Winter Soldier) and, sure enough, Sam Wilson uses one in Falcon & The Winter Soldier. Sharon Carter, however, does not, but is she just a fan of headphone jacks, or is she a secret baddie on Apple's banned list?
The "Problems"
The biggest hint that Sharon Carter is the Power Broker comes following Sam, Bucky and Zemo's confrontation with Dr. Nagel. After proving a useful ally to the boys, Sharon climbs into a waiting car (which is odd in itself) and ominously states, "we've got a big problem... actually a couple of them." Obviously referring to Sam Wilson and Bucky Barnes here, it's obvious that Sharon isn't being completely honest with her old friends. The duo might've caused Sharon some grief in Madripoor, but why would they be a "problem" in terms of her own business interests, unless she were the Power Broker? By this point, the lab is destroyed, Nagel is dead, and the Avengers are hotly pursuing the Flag-Smashers - all of which amounts to a bad day's work for the Power Broker, whomever they might be.
Strolling Past Armed Guards
Sharon Carter has a minimal role in Falcon & The Winter Soldier episode 4 - Sam Wilson asks her to keep tabs on the increasingly erratic Karli Morgenthou, and that's VanCamp done for the week. But as she strolls through the backstreets of Madripoor chatting to Sam on her non-Apple branded cellphone, Sharon passes through a heavy blockade with numerous armed guards standing by. None of them challenge her, or ask for credentials as they might if Sharon were conducting a business deal with a client, and this suggests the heavies are under her own employ. Even the most respected dealer of stolen goods wouldn't hire such intense security or have so many enforcers on their books, but as the Power Broker, Sharon's army of minions makes perfect sense.
Satellite Control
In the same scene, Sharon offers to spy on the Flag-Smashers, telling Falcon that she still has access to a couple of CIA satellite assets. Say what you like about the CIA's organization in a post-Thanos world, but if Sharon Carter was considered an enemy of the state, there's no possibility that she'd still be able to piggyback on their global surveillance system. Assuming this isn't just a convenient plot device, Sharon is either lying about being a wanted woman in the U.S., or the satellites she uses to track Karli's location are nothing to do with the CIA, but under her own control as Madripoor's Power Broker.
Conspiring With Batroc
Falcon & The Winter Soldier episode 5 waves a massive red flag when Sharon Carter is heard conspiring on the phone with Georges Batroc, the notorious mercenary who fought Steve Rogers in Captain America: The Winter Soldier, and Sam Wilson in Falcon & The Winter Soldier's premiere. This apparently isn't the first time Sharon and Batroc have worked together, and later in the episode, Batroc aligns with the Flag-Smashers, hell-bent on killing Falcon. Although it's possible that Batroc is lying about his intentions, and Sharon employed him to secretly help the good guys (just like Nick Fury in Captain America: The Winter Soldier), a partnership with a baddie like Batroc adds fuel to fans' "Sharon is the Power Broker" fire, especially if Sam Wilson's death really is his goal.
The Power Broker's Gender Hints
When a movie or TV show is really attempting to hide a character's identity, they usually avoid being specific about the person's gender, so as to provide the audience with no clues whatsoever. Falcon & The Winter Soldier has been suspiciously insistent that the Power Broker is male, using "he" and "him" on numerous occasions, and the pronouns are so exaggerated, it's almost impossible not to consider some misdirection is at play. Falcon & The Winter Soldier (and Sharon Carter herself) could be manipulating gender stereotypes, perpetuating the assumption that a figure of such power would be male, and thereby taking the spotlight off the real Power Broker, Sharon Carter.