Shadowhunters is back with the second half of Season 2, and we've already got a few major dangers headed Clary (Katherine McNamara) and Jace's (Dominic Sherwood) way.

The arrival of a greater demon in New York City had everyone on edge in the premiere, even the nefarious Valentine (Alan Van Sprang). The one person who didn't seem fazed by Azazel? Newbie Sebastien (Will Tudor). So far, we only know a few things about this new character. He's heroic, understanding, charming... and potentially psychotic.

It's awesome for Isabelle (Emeraude Toubia) that she's found someone who understands her Yin Fen addiction, but this might be a case of "out of the frying pan and into the fire." Sebastien's miracle cure for her addiction withdrawal is a temporary fix until she can kick the habit, but in the meantime, she's putting a whole lot of trust in a guy she just met after he pretty conveniently showed up in time to save her from Azazel.

Shadowhunters Season 2B Welcomes Back Clary's Love Triangle

Speaking of that meet-cute, you may have accidentally mistaken Sebastien for one Jace Wayland during that first fight scene. That's not a mistake, and fans of the books will know why — in the novels, Sebastien turned out to be Clary's demon-blooded bro, not Jace. However, Shadowhunters has been known to deviate from its source material in huge ways, and the cast has assured us that just because we think we know who Sebastien is, it doesn't mean we're right.

"Book fans will know sort of what Sebastian was in that, but as you know with our show, we love to make changes and we love to sort of twist what the expectations are a little bit, which is actually lovely," Katherine McNamara says. "I find it very entertaining as a book fan to see how the writers interpret the story that's been established and sort of give it a new life through the television series."

As for the Downworld, the greatest threat there might be Simon's (Alberto Rosende) newfound ability to walk in the sun.

After drinking a large helping of Jace's pure angelic blood, Simon now has the ability to walk in the sun like a real boy, which has put a target on both his and Jace's back. Plenty of vampires will be understandably jealous of his new, sunny lifestyle, and Simon is only one spilled secret away from putting Jace on the all you can eat menu.

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"He becomes a daylighter, which is kind of funny for Simon because he literally can't catch a break," Alberto Rosende says. "All the vampires are of course like, 'How did you figure out how to do what we've been trying to do our whole lives? And we've been alive for hundreds of years.'"

Here's hoping Simon can keep the secret about his sunny, new ability, or it will be open season on Clary and Jace's carotid arteries. Not all vamps are as polite as Raphael (David Castro) about sipping on Shadowhunter blood after all.

Shadowhunters airs Mondays at 8/7c on Freeform.