SPOILERS for Agents of S.H.I.E.L.D. episode "The Honeymoon" ahead
Five seasons on, Agents of S.H.I.E.L.D. still has the potential to surprise. One of the most unexpected twists in "The Honeymoon" was the shocking revelation that one major character has been brainwashed by Hydra. All it took was a single phone call, and General Talbot became an agent of Hydra.
Hydra has always excelled at brainwashing. Back when they made their grand return to the MCU in Captain America: The Winter Soldier, they'd brainwashed Bucky Barnes into working as their assassin. But the method used in "The Honeymoon" is very different. It's one Agents of S.H.I.E.L.D. has actually featured before, way back in season 2.
The Faustus Method
The first three seasons of Agents of S.H.I.E.L.D. were really the story of the team's battle against Hydra. When season 1 came to a close, S.H.I.E.L.D. had officially been shut down, and Hydra had been exposed. Season 2 swiftly revealed that the bulk of Hydra's organization remained relatively untouched. It saw Coulson begin a dangerous shadow war against Hydra's leaders, most notably Daniel Whitehall, a student of the Red Skull. Whitehall was particularly proficient in what he called the "Faustus Method," a way of brainwashing subjects into serving Hydra.
The Faustus Method involves exposing subjects to hypnosis and mental programming. Victims - like S.H.I.E.L.D.'s Agent 33 - are strapped to a chair, with their eyes forced open. They're forced to look into a stream of lights, while a Hydra brainwashing expert speaks calmly and carefully. The agent would repeat mantras, reinforcing the sense that it was useless to resist, and that compliance would be rewarded. Whitehall seems to have been the most accomplished practitioner of the Faustus Method, breaking S.H.I.E.L.D. agents and "enhanced" individuals like Donnie Gill.
Once the brainwashing is complete, the subject can be sent back to their "normal" life. According to Bobbi Morse, anyone can be a subject of the Faustus Method; the memories of the brainwashing can be erased, leaving the victim unaware that they're a Hydra mole. The brainwashing is triggered by reciting a mantra: "Calm your mind. You know what is best. What is best is to comply. Remember, your compliance will be rewarded." Season 2 offered subtle hints that the mantra would be most effective if it was recited by someone you trust.
It makes sense for Hale to use this technique. She was particularly loyal to Whitehall, and no doubt studied his methods in detail. What Hale may not know, however, is that some strong-willed people are actually able to overcome the conditioning; Creel himself pulled it off in season 2.
The Legacy of Doctor Faustus
In the comics, of course, this kind of mind control is strongly associated with the Captain America supervillain "Dr. Faustus." The MCU adapted Dr. Faustus into Johann Fennhoff, the villain of Agent Carter season 1. Originally a medical officer during World War I, Fennhoff learned that he could use his therapeutic techniques to effectively brainwash subjects into serving him. Fennhoff was leader of the Russian spy agency known as Leviathan, and was exposed and arrested by Carter.
Fennhoff was imprisoned in the same cell as Arnim Zola, who was freed as part of the U.S. Government's "Operation Paperclip." Zola was allowed a chance to build a new life in the States, and to use his genius to serve in S.H.I.E.L.D. In reality, he played a key role in ensuring Hydra's influence spread. It's possible - perhaps even probable - that the cell-mates shared their secrets. Some fans have even speculated that Hydra ultimately liberated Fennhoff, who shared his techniques with them. If these theories are accurate, it explains why the Faustus Method wasn't used on Bucky Barnes. Hydra didn't learn it until after the Winter Soldier had already been brainwashed; no doubt switching techniques partway through would be unwise.
Agents of S.H.I.E.L.D. season 5 increasingly feels like a love-letter to the series as a whole. In this case, the plot of "The Honeymoon" has carefully lifted a Hydra technique that was revealed three seasons ago, and used it to tremendous effect. If the technique does indeed link back to Johann Fennhoff, as many fans believe, then this is also an ever-so-subtle nod all the way back to Agent Carter season 1 as well.
Agents of S.H.I.E.L.D. season 5 continues with “All Roads Lead...” Friday, April 20, on ABC.