Disney+ sure loves to rename a character on an original series. First we had The Child, a.k.a. Baby Yoda and a.k.a. Grogu on The Mandalorian. Then we had Agnes on WandaVision who was Agatha all along. Now, coincidentally on Agatha All Along, Joe Locke's character "Teen" has a secret identity as well.
We knew this was coming. The character showed up with a spell, or sigil, that prevented him from saying his name or any details about his childhood out loud. They actually call him "Teen" for lack of a better moniker. He arrived as a mystery. But by the end of Episode 5 we're well on our way to officially knowing who Locke is actually playing. All it took was one line about Teen being "so much like his mother," some spooky blue magic, a crown, and a sick Billie Eilish needle drop. All signs point to "Teen" being a Marvel comics hero named Wiccan, a.k.a. Billy Kaplan, a.ka. Billy Maximoff, the Scarlet Witch's son.
This version of Wanda and Vision's twin sons, Wiccan and Speed (Billy's brother, Tommy), were introduced to Marvel comics in 2005. So he's maybe better known to millennial comic book readers specifically. They are both members of the Young Avengers team. They're both canonically queer. Billy is a neurotic nerd who practices magic. Tommy is a chaotic juvenile delinquent and a speedster. I for one am psyched to welcome them to the MCU. Billy's boyfriend Teddy is also a member of the team. But before we get ahead of ourselves, here's what you need to know about Billy.
How is Wanda's son alive on Agatha All Along?
At the end of WandaVision, Wanda broke the spell she had inadvertently case in Westview. That included erasing the two boys she created with magic. They died, basically. Then, in the movie Doctor Strange in the Multiverse of Madness, Wanda traveled to a lot of parallel realities and killed a lot of people to get her sons back before accepting that she couldn't. So, respectfully: WTF?? How is Billy here now?
In the original run of Young Avengers comics, a teenage boy named Billy Kaplan meets another teenage boy named Tommy Shepherd who suspiciously looks exactly like him. It's a lot like It Takes Two or The Parent Trap. Their looks and powers pointed to the Maximoff family. But they actually aren't the original, biological sons. They had separate childhoods and don't even remember growing up with Wanda and Vision. This Billy and Tommy are vessels for the twins' reclaimed souls. After the original Billy and Tommy died, their souls were claimed by Mephisto. When the devilish Mephisto was destroyed, Billy and Tommy's souls dispersed and landed at the Kaplan and Shepherd households. (They actually became superheroes before realizing they were nepo-babies. Before he discovers that he is the Scarlet Witch's son and decides to be called Wiccan, he goes by the name Asgardian. That's why, if you look up pictures of Billy in the comics, he's kind of giving Thor.)
But this is the MCU, so things are obviously a bit different. Teen was originally named William Kaplan, who was a completely different kid and lived in Eastview. After is bar mitzvah, he ends up getting into a bad accident as things in Westview got worse. William seems to die, but then Billy takes over his body. He gets the ability to hear people's thoughts which causes him to have some issues acclimating to his "new life." It is also discovered that Lilia was the one who put the sigil on him after reading his palm and seeing what was going to happen to him in the future.
He meets up with Ralph Bohner, who was forced to play Pietro back in WandaVision, in order to find out more about what happened in Westview. He finds out that Wanda used to have twins and realizes that he is really Billy Maximoff. He proceeds to try to find Agatha Harkness in order to go down the Witches' Road and find Tommy who he still feels is alive.
What powers does Wiccan have?
In the comics, he's a practicing witch and also has sparkly electricity powers. He can manipulate reality, teleport, and in the show, at least in Episode 6, it looks like his mind-control powers are similar to Wanda's as well. He can also read a person's mind and talk to them via telepathy.
In the finale episode, we also see that he has the ability to take a soul and transfer it to another body as he did with Tommy. However, whether or not he can do that with his soul because that's his brother remains to be seen.
We also found out that he is the actual creator of the road, showing that he as the ability to distort reality like Wanda, creating a fiction place that everyone thought was real.
There's also a prophecy that Billy will become a god-like world destroyer called the Demiurge. Let's not worry too much about that right now.
How did Agatha know who he was?
That... is a great question. For a while it seemed like Agatha thought "Teen" was Nicholas Scratch, the son she sacrificed to obtain the Darkhold. Rio warned her that that was not true. In Episode 5, he said Nicholas Scratch's name, which confirmed he was not him. The sigil wouldn't have allowed him to say that out loud.
But Agatha kind of knew all along, especially after the door to the Witches' Road appeared when they sang the song. Agatha found out that the reason it appeared is because Billy created it. She also notes that Billy and Wanda have the same tell, which likely the creation of new realities, so she definitely knew a lot earlier than anyone else. Of course, now that she is working with him as his spirit guide, we find out more about how she figured it out later. But for the most part, we now know the truth behind Billy Maximoff.