WandaVision Episode 8 "Previously On..." finally gives us a full (and real) backstory of Wanda Maximoff (Elizabeth Olsen) - something Marvel Cinematic Universe fans have been waiting for since Avengers: Age Of Ultron. While we've known for years about the traumas of Wanda's younger years - losing her parents in the Sokovian Civil War, being experimented on by HYDRA - actually seeing these events depicted onscreen was a much more powerful experience. The sequence where Wanda encountered Loki's scepter/the Mind Stone was especially revealing, as it confirmed a longtime theory about the Marvel Cinematic Universe version of Wanda/Scarlet Witch, and why she Survived those HYDRA experiments
Warning: WandaVision Episode 8 SPOILERS Follow!
What we learn from WandaVision episode 8 is that Wanda Maximoff wasn't some successful experiment in using the Mind Stone to give human beings powers - Wanda was a powerful being whose magical potential was "amplified by being exposed to the Mind Stone. As Agatha Harkness explains, without the power of the Infinity Stone's power, Wanda's magic powers would've "died on the vine." So the Mind Stone simply sparked the power Wanda didn't know she had inside.
The nature of that "Chaos Magic" power is still being defined, but it's now clear that Wanda was special long before HYDRA and Baron Von Strucker picked her up. In many ways, this is one of the main thematic subplots of WanaVision: Wanda ultimately being empowered by finally coming to terms with her own pain and power.
Of course, since WandaVision is Wanda's story, episode 8 sidesteps any questions of how Pietro Maximoff got his speed powers activated by the Mind Stone. That's an important missing detail, actually: Agatha makes it sound as though the Mind Stone resonated with Wanda's magical powers; add Pietro to that discussion and magic doesn't really apply. But mutant powers? Well, they're definitely something the Mind Stone could unlock in a person. Unless there's some kind of speed-magic, mutant powers still seem like the only real explanation for why Pietro gained his speed from the Mind Stone, and why Wanda's untrained magical powers are so uniquely powerful.
Clearly, Marvel Studios is still skirting the line on introducing mutants into the MCU, but it definitely feels like we just took a big step closer to that sort of reveal. WanaVision is compiling all the major Scarlet Witch lore from the comics, so getting Wanda's mutant gene to reveal in the mix seems like a necessary part of that agenda.