Agatha All Along finally made good on its promise. The Marvel series started with a big mystery looming over it: who is “Teen,” the young boy Agatha seemingly adopted and referred to as her “pet”? He tried to tell her all about his identity, but a magical sigil prevented her from hearing any details. But the truth finally came out in Episode 5, and when it did, it confirmed a long-held fan theory... and gave the MCU a convenient addition to a Marvel team-up that’s been building steam for years.
At the end of Agatha All Along Episode 5, Teen and Agatha argue about the death of Alice, which gave Agatha her magic powers back. “That's what it means to be a witch? Killing people to serve your own agenda? No. Not for me,” Teen says. Agatha smirks and responds, “You’re just like your mother.” That sparks Teen’s transformation into Wiccan, aka Billy Kaplan, the magically powerful re-manifestation of Wanda’s son William Maximoff.
