The Marvel Cinematic Universe has not gone out of its way to explain how Elizabeth Olsen's Scarlet Witch got her powers. She and her brother Quicksilver were simply referred to as "Miracles" in Avengers: Age of Ultron. This seemed to be a simple substitute for the word "mutants," a group of Marvel characters who ultimately play roles in X-Men stories. However, at the time, the X-Men characters and mutant stories were not owned by Disney and Marvel Studios, so such a trait could not be used. Now, new details of Scarlet Witch and Quicksilver's power source has been revealed in an MCU-canon book called The Wakanda Files.
Doctor List appeared in Captain America: The Winter Soldier and briefly in Avengers: Age of Ultron. The villainous doctor studied Wanda and Pietro Maximoff. His recording were not part of any scenes in the films but a log the doctor kept was published in The Wakanda Files, revealing new information about their powers.
"After their initial exposure to the scepter's energy, the twins show astonishing improvement," Dr. List writes. "Their own tenacity, a shared abhorrence for Tony Stark and all that he represents, arouses them in ways others subjects never demonstrated. Perhaps that is why the other subjects failed and perished. They lacked conviction." Now, the conspiracy theory hat might be a little tight, but is that a backdoor entry for mutant characters created by Dr. List and Loki's scepter being opened up? Probably not, but how the X-Men will be incorporated into the Marvel Cinematic Universe remains to be seen.
"Pietro's metabolism increases daily, as does his speed," the log goes on. "We have clicked him at 400 meters per second. He has broken the sound barrier and grows closer to traveling at th speed of light by the day. Thermoregulation shows exponential generation of heat and energy, especially when he is moving at his peak velocity. Even when he is placed in an ice bath, his homeostasis remains consistent despite the freezing water. It would seem that the stone ionized his nervous system. He conducts an electrostatic current throughout his body, without any of the effect of electroporation. The resulting expansion of that energy is super-speed unlike anything exhibited by a human being."
Whether or not we will ever see more of Aaron Taylor-Johnson as Quicksilver is unknown and has historically seemed doubtful as the character was killed off in the same movie where he was introduced.
"Wanda's continued progress is vastly different from her twin brother," Dr. List says. "Even I don't believe this is the full extent of her potential. The stone similarly transformed her nervous system, but it has ionized and charged it in ways that have given her an extraordinary ability. Neural-electric interfacing allows her to create bursts of extreme energy using only her mind and the tips of her fingers. The manipulation of this energy permits her short bursts of levitation, in addition to a staggering weapon that only requires her bare hands."1comments
He goes on to note that Wanda is capable of planting new thoughts in other minds, expanding on previous paranoias, and see into the mind of other humans. Dr. List notes Wanda is capable of "psychological warfare."
Some of these details may be explored when WandaVision hits Disney+ later this year.