Silas Weir Mitchell, Bree Turner Silas Weir Mitchell, Bree Turner

"This is the beaver section. Fuchsbau here..."

The placement of Wesen is of utmost importance on this sunny April day in Portland on the set of Grimm. But it's not to keep predator and prey apart; instead it's to differentiate between who's there for the bride and who's there for the groom. Welcome to the wedding of the fox-like Fuchsbau Rosalee (Bree Turner) and wolfy Blutbad Monroe (Silas Weir Mitchell) for the series' Season 3 finale Friday (9/8c, NBC).

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"Everything about this wedding is kind of outré in the world we live in as Wesen," Mitchell tells reporters while dressed in his wedding finery. "There's a Grimm on the altar, there are different Wesen all together — which is less strange than the Grimm being there. It's all about inclusiveness and having a Kehrseite-Schlich-Kennen — a complete normie — who's in on it. But everything about the wedding — the interspecies thing, which is a no-no — it's a big deal." Although Wesen typically tie the knot outdoors, this particular union will take place at a real-life historic log cabin in the woods. Signage for Zimmer Mountain, a pool and spa and bridal cottage are also placed around to convert the private residence into more of a community setting. "We talked about having it outdoors, and it would be great to do it today [when it's not raining], but you can't plan around days like this," Mitchell says. The sunny day is nevertheless still chilly at 8 a.m., and the female cast members clutch hot coffee cups while wearing Uggs and heavy parkas over their dresses. Mitchell adds, "I also think it's a nod to being part of the human realm as well that we're doing it inside."Naturally, it wouldn't be Grimm without a bit more action than catching the bouquet. Mitchell teases, "We say this every year: All hell breaks loose. What's the most complicated, f---ed up thing that could happen? That's what happens. No zombies, but lives change."Check out what's in store for each of the wedding party:

The BrideRosalee bucks tradition again, but not necessarily by choice this time. Although she was set to wear her grandmother's high-necked, heirloom wedding gown, not everybody (read: nobody) was a fan. "I would say 'frumpy' is a kind word," says Mitchell. Turner tried on about 15 new gowns before settling on the strapless showstopper replacement pictured above. And what about granny's dress? "The writers came up with this very creative, funny, happy-accident kind of solution [to necessitate] a new dress," Turner says. During rehearsals, she makes her grand entrance, descending from a staircase, and even though the long skirt almost trips her up, the overall effect is worth the last-minute switcheroo.Fall TV Scorecard: What's canceled? What's renewed?The GroomMonroe doesn't have any similar sartorial concerns, but that's because all of his drama is on the inside. "I'm just dumbfounded, agape," Mitchell explains. "It's just, 'Pinch me. Is this real?' I've gone from being a horologist hermit who went out to get his mail and that's as far as outside as I wanted to go, to someone who's crime-fighting with a Grimm and falling in love with another species. My life has changed so much, and this [wedding] is sort of the culmination of the drawing out of Monroe into the world."The Maid of Honor"I figure very prominently in the finale episode. I'm all over it," Bitsie Tulloch, who plays Juliette, says. As viewers saw in the previous episode, the Hexenbiest Adalind (Claire Coffee) created a potion that would help her impersonate Juliette — to what purpose remains to be seen. "Adalind's pissed with what's going on with her baby and her maternal instincts — however creepy they are — are kicking in, and she's making a mess out of everything for everyone," Tulloch says. "Listen, people are always asking me if things are going on in the love triangle with Renard, and what I've always said is, you've undoubtedly not seen the end of it."The Best ManMeanwhile, Juliette's significant other Nick (David Giuntoli) will wear sunglasses to shield his telltale Grimm eyes from any Wesen who "woge" during the wedding, but that's the least of his problems. "I think Nick feels like a burden to a lot of his people, Monroe, Juliette," Giuntoli says. "In this episode, some stuff goes down because I'm a Grimm. I always I feel like I'm a bit of a pariah. Nick is trying to be a friend to people, and it's probably making their lives worse."The Matron of HonorRemember DeEtta (Laura Faye Smith)? She gave Rosalee grief for being a former drug addict and missing their father's funeral. But she's since since made up with her little sis. This does not, however, mean that DeEtta doesn't still have some issues. As we can see from this clip, she has a marked fondness for wine.

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The "Father" of the Bride

"I have the honor and responsibility of giving away Rosalee," Russell Hornsby, who plays Nick's Portland PD partner Hank, says. "She's without a father, so I've been blessed with the responsibility of walking her down the aisle." Turner adds, "I don't really have any male figures in my life, and Hank has been a friend, a confidante, a supporter. I think it's also furthering the unification of Kehrseites and Wesen, and that we're really standing as a couple above this brave new world of mixing everyone together."

The Party Pooper
Although Adalind is not invited to the wedding (as if!), her influence will be far-reaching. "In light of what has happened in the past, I basically have Adalind repellent. She won't swing back my way ever again," Hornsby says. "She's looking to invade somebody else's space. She's sort of easing her way down the road and making stops in different people's lives. She starts with me and then she goes with Nick and then she comes to me and then goes to the captain and then goes back to Nick and then f---ing with Juliette."

The Wild Card
The new Grimm in town Trubel (Jacqueline Toboni) is "young and she's feisty. She hasn't learned to respect her elders just yet," Hornsby says. She always intends to listen (like when she was told to stay in the car), but bigger issues like saving someone's life always interferes. Like Adalind, she's not invited to the wedding, but one way or another, she just can't seem to avoid trouble.

What do you think will go down at the Grimm wedding? Catch up on the last episode here.

The Grimm finale airs Friday at 9/8c on NBC.