Roswell, New Mexico has made a lot of changes to the original Roswell narrative and its characters, but the one person who has probably changed the most is Kyle Valenti (Michael Trevino).

Rather than a puffed-up jock with some seriously sexist notions passing as overprotectiveness, Kyle is a former jerk turned decent human being. He's even a successful physician with a pretty compassionate demeanor most of the time. Just don't push him too hard when it comes to the whole alien thing, you know?

TV Guide spoke with Trevino ahead of this week's episode of Roswell, New Mexico, which will prove to be a big one for Kyle as he digs deeper into his father's mysterious death. And the whole anti-alien thing? It could be reaching a tipping point very soon.

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How big is this episode in regards to the mystery surrounding Kyle's father and his death?

Michael Trevino: Especially in tomorrow's episode, going into this building, Cauffield, it answers a lot of questions. By the end of the episode for sure, there's just such a shift that happens in Kyle to where things go just in a negative direction for him. Especially in the finale, it just kind of — something breaks him down a bit.

He's been teetering between an anti-alien mentality and a more tolerant one, so are we going to see him reach a tipping point as far as that's concerned, especially if he finds out an alien was involved with his dad's death.

Trevino: Absolutely. I think if there's anything that's going to go full anti-alien, it would be if they are responsible for his father's dearth. I think with this, he's just gathering as much information as he can before he asks for the assistance of anybody else, whether it's Liz (Jeanine Mason), whether it's Alex Manes (Tyler Blackburn). He's just trying to find out more. ... Moving forward, it's what he finds out in Cauffield that pushes him towards a darker area.

Do you think this investigation has helped Alex and Kyle rebuild their friendship and the trust between them?

Trevino: A bit. I love that in our scenes, the way that they are written, there's times when Alex will jab back at Kyle because it's a reminder. Kyle was a dickhead in high school, OK? He was a jerk, and because of that he needs to be reminded, 'You weren't the nicest person, and although you have evolved and you have changed and grown and learned, you weren't too nice to him.' I like that it isn't just full-on, yes they are best buddies now trying to conquer the world and figure out what's going on in Roswell. No, there's still a little bit of uneasiness and it being a bit uncomfortable still. But at the end of the day, they do need one another going through all of this.

Michael Trevino, Roswell, New Mexico Photo: Ursula Coyote, Ursula Coyote/The CW

What's been your favorite part of playing a character that's changed so much from the homophobic guy he used to be?

Trevino: For me, playing Kyle is just somebody who's very grounded and principled, who's just rooted in his reality. In the beginning of the season, life was great for Kyle. Everything was going well for him. He kind of had his life set up the way that he wanted it. But now, being back in town and having Liz back in town and all the nonsense with aliens, he's having to deal with all that. For me, he's very calculated in his decision-making with what information does he want to tell Liz, what does he want to keep from Liz? What does he want to tell his mother, what does he want to keep from his mother? How is he going to help Alex Manes figure out some more information about his father? Is Kyle being played by Master Sergeant Jesse Manes (Trevor St. John)? How do I play his back? I love that Kyle is involved with all the storylines and every character. That's been my favorite part. ... I've been on a series before where I only maybe had one storyline throughout, which was nice, but I wasn't able to be affected by other characters. With this, I'm involved all around, and it's been a joy to work on.

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The scene I've been not so patiently waiting for is when Kyle and Liz confront the fact that they share a sister. Is that anywhere on the horizon?

Trevino: Well, it's an hour show and we're trying [to fit] all of this into 42, 44 minutes? He does tell Liz the truth about Rosa (Amber Midthunder), but at the same time there are so many outside elements going on that this isn't, "OK, let's sit down and talk about this." This isn't a planned moment, it's more like, "I just need to tell you this, and it has to happen right now, and I wish I could tell you differently, but this is what it is." So to get our story moving and because we don't have much time to do it, that's the way that it happens.

You mentioned a darkness coming for Kyle, how will that affect his dynamic with Liz and his other friends?

Trevino: I think Kyle starts to isolate himself. I think when he starts going "to the dark side," he wants to isolate himself and stay away from people and question everything. Question his life and question who his father really was. What's most frustrating, he can't really ask anyone else. He can't trust anybody else with all this information, these secrets he's been told. He's losing his mind really. ... I think at the end though, he just can't take it. You have a breaking point, and I think Kyle has a breaking point. With the finale, I think we've reached his breaking point. How that affects Liz, somebody who's going into the dark side kind of stays away from her. I think he doesn't want to have her involved or be around. But he's also always had this issue with Master Sergeant Jesse Manes, so he may take some of his frustration and anger out on him.

Roswell, New Mexico airs Tuesdays at 9/8c on The CW.

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