It's not always the boyfriend — sometimes, it's the girlfriend.

So is the case for I Know What You Did Last Summer, which revealed that (major spoilers here, obviously) Lennon's best friend/occasional lover Margot was the killer all along. The whole "I know what you did last summer" thing wasn't about the group killing the real Lennon and ditching her body, but about Allison posing as her more popular twin in order to escape any wrongdoing. Margot was in love with Lennon (who, let's be real, definitely contributed to Margot's mental breakdown with her extremely toxic behavior) and had figured out Allison's secret well before Allison confessed the truth to Dylan.

Sara Goodman, the creator of I Know What You Did Last Summer, tells The Dipp Margot's murderous reveal was always the plan.

"I knew Margot was the killer from the beginning, from before the writer’s room — from the pitch," she explains. "Margot was always the killer. I wanted the killer to do it for love. As Margot says, I think in Episode 3, ‘They always kill the ones they love.’ Thematically, Margot really does think she’s doing it for love, to avenge the one she loves."

Now, it seems like Margot — who went on the murder spree specifically so that Allison would confess her real identity — is perfectly fine pretending that Allison is Lennon, because at the end of the day, Allison chose to protect Margot at Dylan's expense. Does Allison love Margot, like she claims, or is this a part of a greater plan to make sure her secret never gets revealed?

"I think she loves both of them," says Goodman. "However, I think it was more of a choice of saving herself. It was her deciding to be Lennon. It was an identity choice. She didn’t see how she could live if she chose Dylan. She would have to pay for what she did. She had to only be Allison, and Dylan doesn’t love her. It’s not that these were conscious thoughts on her part. It’s not that she doesn’t love Margot, but I do think it’s a self-preservation choice — a choice to be Lennon."

Unfortunately, that self-preservation decision comes at a great cost: Now Allison must find a way to ignore the fact that her girlfriend is a psychopathic murderer, which seems almost as hard as the whole twin-switcheroo.

Of course, anyone who has watched I Know What You Did Last Summer, and poured over the show's clues, knows that there were quite a few hints that Margot was the killer all along. We can't blame Allison for not seeing them sooner — but boy, it would have been great for everyone if she did.

Johnny and His Fiance Were the First Victims

Is it weird that Johnny got engaged to his former football coach during his freshman year of college? Very. Alas, Johnny was such a gem — the fact that he was the first one to go, and that his death was orchestrated so that he accidentally killed his soon-to-be husband was unnecessarily cruel.

Yet it's the extra cruelness of Johnny's death that hinted it was Margot who was behind it: Margot said multiple times that she felt betrayed by Johnny for not attending the same college as her, and before that, it's hinted that she's still salty that Johnny dumped her. Given that Margot doesn't exactly have the healthiest friendships (see: Lennon), it kind of makes sense that Margot would exact revenge in this way, even if she never said as much.

Margot Killed People Who Were Close to Allison and Lennon

There's also the suggestion that Margot was jealous that Allison was closest to Johnny out of everyone in the group. Even if Margot was pissed that Allison wasn't really Lennon, it's clear she has some connection to Allison after they spend time together following their summer return. If she was so jealous of Allison's connection to Dylan, then it's pretty safe to say that Johnny could also have been on the chopping block — no pun intended.

The same can be said about Dale, who Lennon hooked up with before her death. As we know from Margot's post-credit monologue, Dale was blackmailing her after she asked him to put the goat head in Lennon's closet, but I suspect it may be more than that. Was Margot jealous of Dale's past with Lennon, and potential to get with Allison, given that she was posing as her sister? It could be why he really met his maker at the end of a blue icee machine.

Margot's Brush With "The Killer" Was NBD

When the killer saw Johnny vulnerable following his attack, he didn't just let him be. The killer chopped his head off! So why would the killer not do something equally as twisted with Margot? Err, I guess we know why now — you can't do a villain monologue without a head.

It's also worth noting that Margot sending herself to the hospital is very in line with her character — she wants to garner sympathy whenever she can, which is what it seems like she's done in the past with her very public social media breakdowns. Basically, Margot has pretty extreme emotional reactions — and, uh, murdering people is about as extreme as you get.

The Killer Documented Everything... Like Margot Does

Margot is an influencer — she routinely documents even the most vulnerable parts of her life, albeit with a glowy filter. That's why it was a pretty big clue that the killer did the same thing, by sending videos of the crimes to the people who would be most affected by it.

"She used social media as an alibi," says Goodman. "It always looked like she was doing things. She had that knowledge of technology as well. I think there is that part of her that is a performer. The drama of that, I don’t think is lost — how she did things and why."

Margot needs an audience in her real life, and as a murderer, she had to document it all, too. No other character on the show was as connected to social media or streaming as Margot was, so this one was a pretty big red flag.

Honestly? We should have seen it coming... but it was a pretty fun ride to the reveal, regardless.

Images: Amazon Studios