Warning, spoilers ahead for season four, part two of You. Should you choose to continue reading and then complain, you are peanut butter on the roof of the TV world's mouth!

Just when you thought you knew Joe Goldberg (Penn Badgley), You proves you wrong yet again. The Netflix drama delivered its darkest and most dramatic twist yet when it was revealed that Rhys Montrose (Ed Speelers), the British political figure who was presented to be the "Eat the Rich" killer in part one, is in fact a figment of Joe's imagination. Yep, that's right: Joe has fully lost it and is a full-on serial killer, having hallucinated all of his previous interactions with Rhys.

In part two, viewers watch as Joe reconciles all of the bad things he has done—including holding Marianne (Tati Gabrielle) hostage after initially letting her go and murdering the powerful father (played by Greg Kinnear) of his posh girlfriend, Kate (Charlotte Ritchie)—before he ultimately decides to end his life in the season finale. 

While Joe initially jumps off of the bridge and immediately regrets his decision as he begins to drown, the Internet's favorite stalker is rescued and lives to possibly kill another day, now with all of the resources and money that Kate inherited. Gulp. 

After our heart rate finally calmed down and our mouth reattached itself to our jaw, E! News chatted with You showrunner Sera Gamble about taking the "big swing" to give Joe a, the "challenging" process to cast Rhys and Charlotte, and how those surprise appearances in episode nine came to be.

E! News: When did the writers decide on that Rhys reveal?
Sera Gamble: We had been talking about something like this happening to Joe for a long time. Because it seems that he gets a little crazier every season. So we asked ourselves, "What is the Mount Everest of how crazy he can get?" And we started to lay things in in earlier seasons to prepare ourselves for that. It's a big swing. It's a pretty iconic thing to do in a story like ours, so we were waiting for the right time.

E! News: If people rewatch earlier seasons will they find little Easter eggs hinting at this twist?
SG: Sort of in that if you watch the episodes where Joe has an especially hallucinatory experience, they've been getting worse over the seasons. He had a head injury in season one and he saw his ex. In [season three], the inner monologue in his head was appearing to him when he was sick, just sitting on the counter and talking back to him. So in that way, we've been thinking of it as we're excelerating towards the big monster version.

E! News: What was the process like to cast Rhys Montrose?
SG: The casting was intimidating because we knew just as much as any love interest we've ever had on the show, this was an actor who was in a lot of intimate emotional scenes with Penn. They needed to be able to hold their own. We needed somebody who had that version of that star quality that Penn does. Luckily, England is known for its actors! So we saw a lot of fantastic men for the role. I had seen Ed in a couple of things before, so I was excited to see him and then he just made the case for himself the second he opened his mouth.

E! News: Was Rhys always going to be the character that Joe created?
SG: Everything was on the table when we started. We were like, is this character male or female? Would they be American or British? We started to hone in on the idea that because this is a part inside of Joe that is essentially trying to help and get through to him, he would see somebody like Rhys that he admired and felt was easy to talk to.

E! News: Because we've only seen Joe stalk women previously, did you ever consider have a female character take on that role?
SG: Love and obsession is certainly not limited to who you want to sleep with. At this point, Joe is a little bit onto his own tricks in terms of his picker is a little off sometimes with women. He's pulled a fast one on himself in that he might not have been thinking about it that way. He himself did not realize he would go to those lengths. For us in the writer's room, it just raises a lot of questions of like, "What else has he done in the last decade that he doesn't really think about the way it actually exists?" There's more fodder there.

E! News: You wanted someone who matches Penn's star quality and viewers really see that in their scene on the bridge. Rhys asks, "Why can't you see yourself the way I see you? I love you." In other circumstances, that is the most romantic declaration you can make. And in this, it is really messed up. 
SG: We did think of it as a very romantic scene. The kind of things that Rhys is saying are no different than other declarations and the one that is popping into my mind right now is Grey's Anatomy's "Pick me, love me, choose me." It made sense for this relationship too. Rhys loves Joe and has been taking care of him and helping him survive for his entire difficult, troubled life. What it finally does is make Joe ask himself the question, "Can I love myself?" Just a very dramatic version while standing on the edge of a bridge.

E! News: While Joe decides to jump off the bridge, he's ultimately rescued and survives. Were there ever discussions about how the show could continue if Joe died? 
SG: When Greg Berlanti and I were developing the series, we talked about the fact that there could be a season or a storyline from somebody else's point of view. So that has always been part of the premise, it's just that we have Penn. Why would we not keep writing for Penn? He just exceeded every expectation we had. That said, I've done a lot of things where people are dead and it's fine. I've written entire seasons where they're just ghosts or monsters or demons. Death is not the end for me, so I don't even really think in those terms.

E! News: Aside from Rhys, Joe's other important relationship in season four was with Kate. What was the process like to find Charlotte Ritchie?
SG: When you are casting the woman of the season, the longer the show runs, the more treacherous that is for any actor coming into audition because it was hard enough when you were trying to follow Elizabeth Lail, but now also our Love, our Marianne. Not only does she have to be compelling in her own right, but also very different than Victoria Pedretti, very different from Tati Gabrielle. I have to give all credit to our executive producer Sarah Schechter, who is the world's biggest Feel Good superfan. It's a great two-season sweet relationship comedy and Charlotte is the romantic lead of that series. So really from day one, Sarah was like, "Can we get Charlotte Ritchie?" And she is very, very busy, but as the process went on, we just kept going back to her knowing that she was both a very formidable dramatic actress and also had brilliant comedic timing.

E! News: Elizabeth Lail and Victoria Pedretti both make surprise appearances in episode nine during one of Joe's hallucinatory spells. What was it like getting them back?
SG: The excitement of seeing both of them was attractive to us as an idea, whether or not we could even justify it. But what ended up happening at that point in the season was that Joe can't trust his own inner monologue and he already has an imaginary person talking to him and stating a certain point of view. We were like, "How are we going to argue the other side? How are we going to move him to a place where he realizes that there is a solution to this problem potentially that he hasn't been considering?" Because Rhys would never bring up that Joe is the problem. He would only point at all of these factors to justify what they've been doing. Who better but the giant squadron of women that he has killed?

Check back with E! News later this week for scoop on what to expect from a potential season five. 

You season four, part two is now streaming on Netflix.