Throughout the course of the show's first season, "Wynonna Earp" sadly learned that blood isn't always thicker than water.

When they were children, Wynonna and Waverly Earp's older sister, Willa, was kidnapped by demons and presumed to be dead. Willa later revealed herself to be alive, and appeared willing and able battle supernatural threats alongside her sisters -- until Willa's true nature and allegiance to Revenant leader Bobo was eventually revealed.

In tonight's Season 1 finale of the IDW-produced comic book-based show, the Earp sisters' bond will be tested like never before, as they must stop Willa from unleashing an incredible evil capable of destroying them and their hometown of Purgatory.

Star Melanie Scrofano, who brings Beau Smith's title character to life, spoke with CBR News about the Syfy series' freshman season, and how sibling loyalty will be tested -- to a possibly fatal degree -- in the season finale.

CBR News: Wynonna was a loner with a chip on her shoulder before returning to Purgatory. How did reuniting with her younger sister Waverly and facing her heritage change her?

Melanie Scrofano: Waverly embraced everything about her heritage and their family. Wynonna had done the exact opposite. She thought it was maybe made up. She was called crazy. So, when Waverly, who was supposed to be normal and is -- because everyone considers her the normal one and the sane one and the good one -- when she started really diving into the Earpness of it all, that opened a door for Wynonna to say, "Okay, if she's doing it, then I guess I have no choice."

For an instant, Willa seemed poised to replace Wynonna as the Earp heir responsible for Peaemaker and demon hunting. How did that sit with Wynonna? Was she relieved?

Finding Peacemaker really gave Wynonna a sense of purpose that she never had. When Willa came along and reclaimed her place, Wynonna found herself again going, "Well, now what? Now what's the point of me?" As happy as she was that Willa was back, any sense of purpose that she had found over the course of the season and coming back to Purgatory, she basically lost again. There was that duality of happy to find her sister and then realizing when her duty was taken away from her, how important it actually was to Wynonna. That was the catalyst for her to realize, "Maybe this is important to me. Maybe I shouldn't complain so much."

Family means everything to Wynonna -- so how does she deal with Willa's betrayal?

I don't think Wynonna wants to deal with it. I don't think Wynonna wants to believe Willa is capable of betraying her. Last time Wynonna saw Willa, they were kids. Willa was 13, and Wynonna was 10. Willa and Wynonna were two peas in a pod and best friends. Willa was her idol, and she had this purity about her. So when Wynonna finds her again, it's impossible for her to believe that isn't who she is deep down. Wynonna spends a lot more time than she should justifying for Willa. I think Wynonna refuses to believe what Willa really is. Even in the end, Wynonna can never really accept it.

Emotions are running high in the finale. Where are Wynonna's head and heart when it comes to Doc Holliday and Dolls?

In watching the episode, it's so clear to me, as a viewer. But, when I was playing it as well, you get the sense that Dolls has such strength and courage. When Wynonna wants to go off the handle, he's there to reel her in. With Doc, he's got the wisdom of the ages. He can tell a story about a dog and says something very profound. Both of these men are so important to her for different reasons. I don't think she's really complete without either of them there to help her.

Wynonna has a lot to consider, and some hard choices to make. What's affecting her decision making going into this showdown with Bobo and Willa?

I'd have to watch it again and maybe I'd change my mind, but what I was taking away from it was, yes, she's fighting for good. She's fighting to keep Purgatory safe. But what was really her fight was to get Willa back. Wynonna wanted to get her Willa back. That whole fight at the end is about Peacemaker and the gates and Purgatory, but it's also, "Willa, you can't have turned. Prove to me you haven't turned."

I really love how Waverly becomes her own hero. On a personal level, she comes out to Wynonna. She takes things into her own hands. She trusts her instincts against Willa. As the big sister, I'm pretty proud of that. I also think all four of us -- Doc, Dolls, Wynonna and Waverly -- solidified as a team. We truly become a team in this episode. I was buzzing after [episode] 13. Every single person's performance was incredible. We learn more about the Earp family secret, which will really make for interesting developments in Season 2 if we get it.

Doll's boss insinuates she knows some deep dark secret from Wynonna's past, but never spells it out. Did you go to executive producer Emily Andras to fill in the blanks, or just accept that would be explained later on?

I know it will be explained later on because Emily is amazing about those things. I wanted to trust it. I didn't want to fill in too many blanks because I love discovering how things unfold. I know Wynonna has done some bad things. We have talked about what her past looks like. As far as specifics, I didn't want to know too much.

Lastly, what were your thoughts on the cliffhanger ending and what it means for Wynonna moving forward?

It's going to make all our relationships a lot more complex. We have an uphill battle, for sure. Not only with whatever is out there, but also because of what's within each of us. It's going to really make it a challenge to fight what's going on because the dynamics within the group are definitely going to change a lot.

"Wynonna Earp" closes out its first season June 24 at 10PM on Syfy.