Dean Cain made his long-awaited return on Monday's Supergirl as Alex (Chyler Leigh) and Kara's (Melissa Benoist) father. However, Jeremiah's homecoming wasn't the happy family reunion his daughters or good friend J'onn (David Harewood) had expected or hoped it would be.

After rescuing Jeremiah from a Cadmus transport van, Alex and Kara were so overwhelmed by having their father back in their lives that they didn't even stop to consider the scenario through which it came to pass. He was welcomed back into their hearts and even into the DEO without a moment's pause, which seems a bit ridiculous for a secret organization (but then again the lax security protocols at the DEO are nothing new). The only person who was remotely suspicious of Dr. Danvers' sudden return was Kara's new boyfriend Mon-El (Chris Wood) and he made his feelings known — at Jeremiah's welcome home dinner, no less — which naturally put a strain on the couple's very, very young relationship.

Of course, Mon-El was eventually vindicated when it was revealed at the end of "Homecoming" that Jeremiah had not only been been heavily upgraded by Cadmus — he had a cyborg arm and was able to shield his thoughts from J'onn — but was also working with the villainous Lillian Luthor (Brenda Strong) and Cyborg Superman (Harewood) to steal the DEO's national alien registry.

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The hour was an emotional rollercoaster for the Danvers women but especially for Alex. Jeremiah's betrayal rightfully devastates her and the effects of what transpired are something that star Chyler Leigh says will stick with Alex for a little while.

"It stays. It maintains," says Leigh, whom TVGuide.com recently caught up with at a press screening along with executive producer Andrew Kreisber. "It's like any kind of parent/child relationship, especially because they've been apart for so long. Alex wholeheartedly wants to believe in one particular thing and just really believes that everything is pure and good on his behalf. Once you start to see how deep the rabbit hole goes and where his loyalties lie one way or another, it's heavy. It is definitely very emotional, very heavy."

TVGuide.com also asked Leigh and Kreisber about Cadmus' plans, what's next for Alex after discovering her father is no longer the man he once was, and whether we might eventually see a Lois and Clark reunion.

What can you tease of Lillian's and Cadmus' plans?

Kreisberg: It's a shimmy on Lillian's desire to rid the Earth of aliens. It's an interesting debate in the next episode between Jeremiah and Alex [about] if his plan is any more humane. And some of the talking points in the episode, I think, are reflective of the current debate in our world about dealing with immigrants, which we were very conscious of and wanted to speak to that.

So Dean Cain is back for more than one episode?

Kreisberg: Mmhmm.

Leigh: Daddy Dean ain't dead.

Will you say how many episodes he'll be in for the current season?

Kreisberg: He's in [next week's episode], and we're still figuring out how we're going to wrap it all up in a nice little bow at the end of the year.

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Dean Cain and Chyler Leigh, <em>Supergirl</em>Dean Cain and Chyler Leigh, Supergirl

How enhanced/different is Jeremiah? He has the arm and J'onn couldn't read his thoughts. Is there anything else?

Kreisberg: The Cadmus people have been made immune to J'onn's telepathy. It's like, the Martian Manhunter, he's so powerful it's almost too powerful for a weekly series with all the things he can do. If we really deployed him at his full comic book power arsenal no one would be able to pull anything off of anybody. I mean, he's super strong, he can fly, he can phase through matter and he can read minds. Good luck trying to pull one over on them.

Is Alex keeping it hidden that she let Jeremiah go?

Kreisberg: The question of where do Alex's loyalties lie plays a major part in the next episode. Battle lines are drawn a little bit, which is interesting because it's — what I love about this episode and the next episode is, no one's really wrong in a way. Everyone, whether it's Mon-El or Kara or Alex or J'onn - especially the stuff between J'onn and Alex in [Episode] 15 — everyone is doing it because they love each other, even Jeremiah. Everyone is doing what they're doing out of a sense of love and to keep the people that they love safe. And that's why Mon-El did what he did. And that's why Kara does what she does. It's why Alex does what she does.

To me that's the most interesting stuff because ... it's the best kind of dramatic conflict, where everybody's right and everybody's wrong. Everyone's doing what they're doing because they care about each other not because of some evil. And you can only do that if you've done two years' worth of table setting, of setting up these characters, setting up the J'onn and Alex and Kara dynamic, setting up this long road for Mon-El and Kara, and Kara and Alex's relationship getting deeper and deeper and closer and closer so that you can pay all this off by having it all come to a head in an episode.

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Jeremiah also called out Mon-El. When are we going to see a little more resolution on that front?

Kreisberg: The Mon-El secret sort of comes to light in Episode 16, so you don't have much further to go.

So far in the last two episodes you've done a good job with Kara and Mon-El where even when they're deciding to come together something comes up to illustrate a conflict between them. Are you able to continue doing that moving forward? Or are there some weeks where they're just happy?

Kreisberg: I think they are happy together. I think part of their happiness is the tension, you know? It's sort of where they live and we love those banter-y scenes between them when we have this sort of Sam and Diane or David and Maddie from Moonlighting kind of dynamic between them. For us what was so much fun about this episode is, usually Mon-El is in the wrong and it is sort of an episode about Mon-El learning to be a better hero. In this episode, ironically, it's Kara and J'onn and Alex [who] are so close to the problem emotionally that they can't see it, so Mon-El is actually the one who's the most clear eyed, which was an interesting perspective to put him in.

When his secret or identity becomes known, how is that going to affect their relationship?

Kreisberg: It's going to cause some problems. I think what's interesting about it is, he doesn't quite get it's the cover up not the crime, which I think is really the issue. I think about Kara sometimes in terms of Barack Obama. Like, he had to be the best version of himself all the time for a variety of reasons. You've often read about that or people have talked about it like, he could never take the bait, he always had to be the most mature and the most reasonable and the most sensible and the most forgiving because that was what history and the world was asking of him. And I feel like that for Kara too where because she's Supergirl she has to be the best.

Opening herself up to a relationship, whether it was trying to do it with James or trying to do it with Mon-El, it takes a lot for her to sort of put herself out there and let somebody in, because when you do that you're opening yourself up to a lot of messy stuff.

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Will we be seeing Jeremiah interacting with new big bad Teri Hatcher at some point?

Kreisberg: We'd love to. They would love to. Yeah, I mean, there's a plan [laughs]. If we can execute the plan. ... We've known Dean for a long time now and we're just getting to know Teri, but in the best examples of the legacy casting that we do, whether it's John Wesley Shipp or Helen Slater or Lynda Carter, all of them are so proud of the contribution that they made in the past and are so proud and happy to be part of our show moving forward. Again, we didn't know Teri before this casting process and she's turned out to be the exact same way, so she is in this for the fans and knows what her being a part of this means to so many people. So they're both really excited to give back.

Is there anything more you can say about her character and what we can expect from her?

Kreisberg: I think the most amazing thing watching the dailies of her ... she is so not playing Lois [Lane] and she is so not playing any character I've ever seen her play before. I mean, she's so not Susan from Desperate Housewives. She's really playing something completely different from was in her repertoire of all the things that she's done. And she's doing it amazingly.

Leigh: She can say one word and all of a sudden the way that she says it you're like, "Oh I don't want to cross her." She has a lot of power in that teeny tiny frame of hers.

When is her first episode?

Kreisberg: You see her for the first time in [Episode] 15.

Lastly, have you booked a Cat Grant [Calista Flockhart] return?

Kreisberg: We're working on it. We love Calista, Calista loves us. She loves the show. She has other commitments and family and what not, but we're trying to work it out.

Supergirl airs Mondays at 8/7c on The CW.

This interview was edited and condensed.

(Full disclosure: TVGuide.com is owned by CBS, one of The CW's parent companies.)