Agatha All Along: Who Is Rio Vidal, and Why Can't the Green Witch Kill Agatha Harkness?

Rio Vidal can't kill Agatha Harkness, and I think the reason may be a bond or spell between the two witches that forbids them from harming one another. Aubrey Plaza's Rio, the green witch of Agatha All Along, is one of my favorite new characters in the MCU, and after the show's dual premiere I wanted to dig into where she came from, who she really is, and why that fight with Agatha ended the way it did.

Spoilers follow for episodes one and two of Agatha All Along, as well as WandaVision. I'm also working in a scoop or two along the way, and I'll flag those when we reach them.

Rio Vidal posed as a federal agent to get close to Agatha in Westview

The first episode opens with Agatha living in a dazed, fake reality as Agnes of Westview, where she is a cop solving a murder and all the clues lead back to her. She couldn't recognize that she was trapped inside her own spell until Teen and Rio showed up to snap her out of it.

Rio enters the episode posing as a federal agent, Agent Vidal to be specific, and she does it to get closer to Agatha. Shortly after Agatha breaks free of Wanda's hex, Rio shows up in all her murderous glory, and we learn two things: she can't really kill Agatha, and sucking up Rio's powers would also kill Agatha.

Agatha and Rio clearly share a history, and Agatha is bad at hiding it

Agatha and Rio obviously have a history. It shows in the heavy tension of their fight, and press material and interviews have suggested a romantic relationship between the two witches. The black heart on Lilia's list also hints at a heartbroken past.

Agatha is doing a bad job of hiding that relationship. She grabs Mrs. Hart, hence the heart drawn on Lilia's list, to stand in for the much needed green witch, because Mrs. Hart likes to garden. It's the kind of thing she'll do to run away from her ex, and she isn't doing it well.

A scoop from Can We Get Some Toast said Rio is the first green witch

Rio's history and motivations were kept secret from the press, so I want to return to a scoop from Can We Get Some Toast. This isn't a major leak and it isn't a huge scoop, but it does point to how strong Rio might be: they mentioned that Rio is the first green witch.

Being a green witch is already incredibly powerful. Without ranking these witches too strictly, I'd argue Rio sits right under Agatha's powers, if not level with them. In theory a green witch can heal and commune with nature, but since this is the MCU we have to heighten that. Could she reanimate someone whose body is decomposing in the earth, perhaps? And if she's the first green witch, that could make her the first witch to commune with nature, which would make her ancient and full of wisdom.

I think the first green witch detail is likely accurate, because way back in 2023 Can We Get Some Toast said Rio's heart is black and beats for Agatha, which Rio says almost verbatim in the episode. They also described the beginning of the episode up until the fight scene, so I believe they had some genuinely accurate scoopage.

Rio's relationship with Agatha may predate the Darkhold and her 1693 trial

Rio being ancient wouldn't surprise me, because she hints at it herself. She asks how long it has been, and says that since Agatha acquired the Darkhold, "you hid behind all that dark magic."

So I assume they started their relationship before Agatha went crazy from that magic, maybe during or before her trial in 1693. Something happened that clearly split the two apart and left Rio searching for her, because Agatha had been hiding behind the veil of Darkhold magic ever since.

Rio may be bound by an old witch rule against harming your own coven

During their fight, Agatha and Rio have a telling exchange: "You can't kill me. It's not allowed." There are a lot of rules to witchcraft in the MCU. We've learned through Agatha All Along and WandaVision that there's no practicing dark magic, and there are rules around the coven.

Jac Schaeffer mentioned in different interviews that the team learned different rules through their research, and one significant rule in pretty much every TV and movie coven is that a witch shouldn't harm her own coven. We see how everyone reacts to Agatha with disdain, and that stems from her killing her own coven. So I believe Rio can't kill Agatha because it's against witch rules, and if Rio is the first green witch, she probably stands by it because it's an old rule.

It turns up in Hocus Pocus, and it's in American Horror Story: Coven, where a witch should never betray her coven and killing counts as betrayal. Even in American Horror Story, I think they had to stand trial over the redheaded witch, and she burned to death anyway at the end.

The death tarot card hints Agatha may have taken Rio's heart

Realistically, Rio could kill Agatha if she wanted to, but I think something is physically stopping her. In the promotional material released a while back, we got six tarot cards. The first was Death, which usually depicts the Grim Reaper, but here it looks like Rio Vidal. In Death's hand is a flower and a heart, though the heart doesn't look black.

That links to another exchange between Rio and Agatha: "You don't have a heart." "Yes I do. It's black and it beats for you." The card may symbolize what Agatha has done to Rio. Like Aubrey Plaza said, Rio has plenty of layers. She's a little crazy, very dangerous, and can get physical at any moment, which feels like how they played things when they were together.

In their messy breakup, Agatha might have physically removed Rio's heart through witchcraft or a specific spell, and it has since turned black and stopped beating, almost as though she's bound. In my earlier piece on the tarot cards, I theorized this could symbolize Rio healing from a broken heart and waiting for Agatha to reappear on her radar. Now I think she can't kill Agatha because the two of them performed a spell that forbids them from harming one another. That would explain why she physically couldn't kill Agatha, and why Agatha would die if she tried to take her powers.

Why taking Rio's powers would kill Agatha

Agatha saying that absorbing Rio's powers would kill her is something new we learned in this episode. We saw what she did to her coven, and she even consumed some of Wanda's powers in WandaVision, and neither time killed her. The way she mentions it now, as though they both know Rio's powers would be fatal, is interesting, and it's why I think there's a bond or spell between them.

It could also be that Rio's green magic is uncontrollable or too volatile for her. Theoretically witches can dabble in a little of everything, but these witches are associated with specific subgroups like divination, potions and protections. They have different magical abilities that Agatha can still take, and it's only Rio's that would kill her, again possibly because of a bond or magical connection they share.

Fan theories say Rio could secretly be Morgan Le Fay, Enchantress or Blackheart

There has been a lot of speculation that Rio isn't who she says she is, and that Agatha's long lost lover is actually a phony. One theory is that she's Morgan Le Fay, a dark, ancient, villainous sorceress from the comics who comes from the King Arthur legends, also features in The Runaways, and is in possession of the Darkhold. Another is that she's Enchantress. There are two Enchantresses in Marvel Comics: one was an enemy of Thor, and the other got their powers from Loki.

People have also suggested, given her black heart, that she could be Mephisto's child Blackheart. In the comics, Blackheart is Mephisto's son, first seen in 1989's Daredevil issue 270, and has encountered Daredevil, Spider-Man and Wolverine with supernatural abilities that make them insanely powerful. Because of the black heart line, people think Rio might be a gender swapped version.

But Rio said "I have a black heart," which to me means a physical black heart, not her name. The only part of this theory that makes sense to me is that Marvel has gender swapped comic characters before, and it would be very fun. Still, I think the black heart reference is about her actual bodily heart.

Aubrey Plaza teased a big reveal for Rio and a possible MCU future

Aubrey Plaza has alluded to a big, shocking reveal behind her character, so Rio is something of great importance, not just to Agatha but to the show. Her being an original character, unlike the rest of the coven, is also noteworthy, and casting Aubrey Plaza may suggest Marvel wanted her around in the future of the MCU.

At the time, that future still included projects like Doctor Strange 3, Midnight Sons, a Scarlet Witch solo movie, possibly a Moon Knight season 2 and, hopefully, Blade. There was a long list of supernatural projects for Rio to get her hands into, and I expected this season might show how Marvel planned to use her going forward.

Is Rio really the first green witch bound to Agatha by a spell, or is she secretly someone else?