The 'Supernatural' finale will have 'serious repercussions' and one 'Oh sh*t!' moment

Supernatural is closing its 12th season with back-to-back episodes on May 18, and the veteran drama is preparing to go out with a bang, as usual.

First, Sam (Jared Padalecki) and Dean (Jensen Ackles) have to contend with the British Men of Letters, who are hellbent on wiping out all the American hunters; then they'll have to face off against Lucifer, who is on the verge of bringing his satanic child into the world (and we're guessing the little bundle of joy isn't planning to promote peace on earth when he arrives).

Thankfully, given these dire straits, the show has already been renewed for Season 13, which will include an animated episode that -- we're not kidding -- will feature a crossover with Scooby Doo, as we learned at The CW's upfront presentation.

But before Sam and Dean can sample any Scooby Snacks, they'll have to unbrainwash their mother, Mary (Samantha Smith), who is currently working with the limey Men of Letters, and get Castiel (Misha Collins) back on their side for the fight against Lucifer -- since their angelic sidekick is currently feeling disturbingly protective over the devil's hellspawn.

Mashable spoke to Collins direct from Iceland, where the actor was on a trip with the winners of last year's GISHWHES (the Greatest International Scavenger Hunt the World Has Ever Seen), an elaborate game the actor devised back in 2011, which encourages participants to create art and commit acts of kindness across the world. Registration for the 2017 hunt is open now, if you're looking to test your creativity and potentially win a trip to Hawaii.

Read on for Collins' hints about the Supernatural Season 12 finale and what to expect from Season 13, including why he's looking forward to seeing fans' reaction videos after tonight's episodes air.

It wouldn’t be a Supernatural finale without Castiel being brainwashed or otherwise not in his right mind: How did you approach this version of Cas versus the other iterations?

I love that there’s a year-in, year-out touchstone that we can count on here. [Laughs.] Brainwashed is not a terribly inaccurate term -- Cas has been sort of taken over by his single-minded commitment to this new mission, which has also imbued him with a new power. We're gonna see him at the strongest that he's been in a long time, but in some ways he's also compromised -- his judgment is compromised.

Once again, there's gonna be some pretty serious repercussions; it's gonna be good. I think there will be a lot of conversations after the finale online. I really wanna see the reaction videos of the people watching the finale.

Are we looking at a cliffhanger ending, or is there some closure?

In some respects, there's more closure than we typically get -- there's some pretty final-seeming repercussions. I'm, as usual, trying to parse my words carefully here. But there's also a new big bad of the show, so there's definitely a To Be Continued component here that's gonna keep people on the edges of their seats for the beginning of Season 13, which is a very large number of seasons.

Showrunner Andrew Dabb has said this will be the most meta finale the show has ever done, can you give us a hint as to why?

I'm trying to think about how I could talk about that without revealing too much ... No, I've got nothing for you. Maybe I should just say I agree with Andrew, because Andrew's always right and he's so handsome and pretty.

He also said that we’ll have a good idea where Season 13 is going from the finale -- what can you say about the direction of next season?

I think that we're seeing the rise of the influence of Lucifer and his master plan, and we're seeing a big and formidable enemy. The whole thing is punctuated with a very compelling "oh shit" moment, so I think it does lead us all to have a sense of what the framing is for the next season.

The theme of family is central to Supernatural, and Cas hasn’t had much chance to explore his paternal side with Claire Novak because of the Jimmy baggage. Is this protectiveness over Kelly’s baby going to stir up parental longings?

Yeah, I think he's very vulnerable to feeling like he's a member and like he's wanted and needed, and at this moment, he feels like he has the opportunity to be a protector and a caretaker to this mother and her unborn child. I think it engenders a sense of purpose in Cas that he hasn't had for a long time. There's something -- maybe it's inherent to his personality or to angels in general -- to be able to operate as a true guardian angel and to feel like he's a member of a family, is a very powerful thing for Cas.

Will we get to see the vision of the future that Lucifer’s baby showed Cas in episode 19, which apparently inspired his loyalty?

I actually don't know the answer to that -- I'm not sure how that's going to get edited together in the end, so we may, but I'm not sure.

We’re in year seven of GISHWHES now -- what’s the biggest change you've observed year to year?

One of the things that's changed over time is that it's just grown into more of a community -- there are lots and lots of people from over a hundred different countries that now participate. It started out more as this scrappy little thing that people felt maybe like they were doing almost independently, and now it's a real community of people that look forward to it every year and have their own secret codes.

But a big thing for me is that because it is growing, the impact that we're able to have is growing ... we're able to do cooler, bigger, better things every year. Last year one item in the hunt was to help Syrian refugee families in Lebanon, and the outpouring of support that came in was so astonishing and I just got photos a couple days ago from these families moving into their new apartments; these are people who were on the verge of death six months ago and now they're in school and cared for.

Are there any projects your charity, Random Acts, is currently working on?

Right now, Random Acts is finishing up construction of a free high school in Nicaragua, that's our biggest project. It's a really beautiful building, it's serving students that have been kicked out of the public school system, so single moms -- if you get pregnant in school in Nicaragua, you're not allowed to come back to school, so this school provides services to single moms and other students that have been left out.

The final two episodes of Supernatural Season 12 will air Thursday, May 18 starting at 8 p.m. on The CW.