Big franchise movies don’t always reveal key plot twists in their trailers, but this is exactly what happens in Warner Bros’ final look at Fantastic Beasts: The Crimes of Grindelwald. It doesn’t just have tons of new footage, it confirms a major fan theory that adds a shocking connection to Harry Potter. We now know Claudia Kim’s new character is in fact Nagini, Voldemort’s future killer snake and horcrux. And that could mean Grindelwald now has a way to lure Credence to the “dark side,” much like another great villain once did to a powerful young man in a separate prequel series.

Fans have theorized as far back as the first cast photo released last November that Kim’s new character, previously known as Maledictus—the main attraction at a magical circus who carries “a blood curse that destines her ultimately to transform into a beast”—would become Nagini. Not only does this trailer satisfy this theory with Credence calling her Nagini before she turns into a giant snake, Kim herself confirmed as such in an interview with EW where she said we will see “another side” of the character, “a wonderful and vulnerable woman” who will be very different than the vicious creature we will come to know.

While it’ll be fascinating to watch her sad transformation to true evil, this is also a potentially monstrous development for Ezra Miller’s Obscurial Credence. After his escape from New York at the end of the first film, we will find him traveling with the magical French circus from which Nagini is trying to escape. Credence and Nagini, who Kim described as “two broken souls,” will form a very close relationship and try to help one another.

We already know of Nagini’s horrible fate, and that points to a very difficult, possibly terrible choice that will have to be made by Credence, a loner who has major trusts issues. He was abandoned by his real mother and abused by the wizard-hating Muggle who adopted him, and then he was used by Grindelwald (posing as Percival Graves) to get to his sister who he believed was the real Obscurial. Combine that distrust and hatred for the world with the fact no Obscurial has ever lived past adolescence or learned to control their Obscurus and you have a very lost, very dangerous, very scared young man looking for a meaningful connection—one who might be the most powerful wizard ever. That’s what Grindelwald was after in the first film, where he seemingly ruined any chance he would ever have of getting Credence to join him.

Except now Credence has found someone he can relate to, and someone he might fall in love with. What would he do for her? What would he be willing to sacrifice for the only person he cares about in the whole world? Will he follow her anywhere—to anyone? With Nagini running out of time and options, how soon will she turn to a Dark Wizard promising her salvation? We know in a war where all wizards must choose sides, some seemingly good ones will surprise us by fighting for Grindelwald. Since Nagini’s going to end up alongside Voldemort eventually, she might soon stand with Grindelwald first if it means saving herself.

And if she does, could Credence’s love for her be the reason he joins the dark side of the wizarding war? We know the dark path Nagini will slither down. The question is whether Credence’s love for her will make him follow the same one.

What do you think this huge revelation means for Credence’s future? Let us know your thoughts!

Images: Warner Bros.