'First Kill' Ending Explained: What Happened to Theo?

First Kill has landed on Netflix and the vampire teen drama has a lot in store for its viewers from start to finish.

The show, which is based on V. E. Schwab's short story of the same name, follows teens Juliette Fairmont (Sarah Catherine Hook) and Calliope Burns (Imani Lewis), who fall madly in love with each other.

The only problem is that Juliette is a vampire and Calliope is a monster hunter, and both of them are determined to have their first kill.

It's not just the couple involved in the drama as there's Juliette's mother Margot (Elizabeth Mitchell), father Sebastian (Will Swenson), and sister Elinor (Gracie Dzienny), Calliope's siblings Theo (Phillip Mullings Jr.) and Apollo (Dominic Goodman) and parents Talia (Aubin Wise) and Jack (Jason Robert Moore).

Warning: This article contains spoilers for 'First Kill'

'First Kill' Ending Explained: What Happened to Theo?

Juliette and Calliope may be the stars of the show, but theirs is not the only forbidden romance in the show, as the seventh episode "First Goodbye" sees Apollo and Elinor succumb to their desires.

Things don't get far between the pair, though, because Apollo's half-brother Theo stops them only for a fight to break out and Theo gets killed in the process.

Elinor uses her vampiric powers to hypnotize Apollo into forgetting everything that happened in the lead-up to Theo's death, and when she leaves and he realizes what happened he calls Calliope, who runs to his side with Juliette in tow.

When the Burns siblings return home though they see Theo at the dinner table, alive and well and laughing with their parents.

It is shortly revealed that Theo is now a vampire, and towards the end of the episode Juliette reveals to Calliope that she is the one who turned him because she didn't want to see her hurt.

The act causes a huge rift between the young couple and Calliope warns that she is going to figure out a way to kill Juliette and other legacy vampires like her.

Meanwhile, Jack is determined to kill Theo now he has become one of the monsters they are trained to destroy, but Talia decides to save him and helps him escape by bringing him to Juliette's estranged brother Oliver (Dylan McNamara) to live among the monsters there.

Why 'First Kill's' Season 1 Twist Was Essential to V. E. Schwab

Schwab spoke to Newsweek about her thoughts on the Season 1 finale's big twist, explaining that it was one of the storylines she brought to the table for the TV adaptation of her short story.

"Well, actually, that is one of the plot elements that dates all the way back to the bible [she wrote for the show]," Schwab said. "So, that's one of the only elements that I brought into the room and I said 'I want this' and like fought for it every single time it came up moving towards the end of the season.

"I was like, 'I want this I want this I want this!' I mean, I didn't have the constant context of the bible, it's completely different, it happened a different way, but it always happens in relation to Juliette in the way that it does in the show.

"It's interesting because obviously I'm not responsible for casting out the whole sequence around it, or the relationship with Talia in the same way, but it's really interesting.

"It's such a point in Coming Out narratives, being cast out of the family after having a transition, having an awakening in this way, and so I thought it ended up really powerful because it's one thing to have the girls breakout, you have this expected form that we're playing with.

"But, I think we do it as a completely new level too, and it really reminds us that just like Romeo and Juliet it's actually about the families as much as it's about the two star-crossed lovers.

"This is a show where we have the potential to start breaking the siblings down and looking at what happens when those cracks go deeper than just one character on each side."

How Sarah Catherine Hook Felt About Theo's Fate

Hook, whose character Juliette is the one responsible for Theo's fate, told Newsweek that the plot twist was completely unexpected for her.

"It's so good, I did not see it coming because we were given the scripts kind of one by one as we were filming them," the actor shared. "I actually read the script with Imani in my trailer and every time, after each scene, we just kept screaming louder and louder."

"We were so excited! And then when the Theo stuff happened, I mean it was just so clever, because Felicia wrote it —Felicia Henderson, our showrunner, wrote episode eight— and we just thought, 'Oh God that was so genius to take a Burns family member and have now this battle within their family.'

"I just thought that was just so clever. Yeah, I mean, I'm really, really excited for people [to see it]. I'm excited to see people's reactions to that."

First Kill is out on Netflix now.