Brenden Bullock boasts far more Portland-native cred than most. “My family on my dad’s side came to Portland on the Oregon Trail in a covered wagon,” says the 27-year-old. So when he moved to Seattle in 2007—first, for college at Seattle University, then staying for a job—he wasn’t about to throw away his hometown soccer team pride.

“I have a deep spot in my heart for Oregon, and I wasn’t about to give that up for a Seattle team,” he says. So he kept up his Timbers season tickets, even though he can only make a third of the home games. But how would he let his fan flag truly fly on enemy turf?

As it turns out, Bullock would soon find other like-minded Timbers Army exiles.

Ed Pham, age 31, another Portland transplant to Seattle, had earlier briefly contemplated making the jump to the Sounders’ Rave Green, when the Timbers still played in USL and Seattle had the sole Cascadia team in MLS. But a visceral reaction prevented him. “I just couldn’t do it,” he says.

So eventually, prior to the 2013 season, Pham, Bullock, and other Timbers fans hiding in Seattle found each other through social media. They soon banded together to form Timbers Army: Covert Operations (or, rather awesomely via acronym, TA:CO).

TA:CO has more than 900 members in its private Facebook group, and some live beyond Seattle –but it’s primarily a supporters’ group for Timbers fans in the city. They even dare to go out in public, hosting watch parties at bars the Ballard Loft and the Angry Beaver.

The latter bar hosted the official TA:CO watch party for last year’s MLS Cup final. The event drew one Columbus Crew SC fan in full yellow-and-black regalia, unaware that there’d be a 100-strong Timbers takeover in what is normally a Canadian-themed hockey bar.

Photo by Holly Cameron

That’s all pretty public stuff—but, as the name of the group indicates, TA:CO does, indeed, embark on covert operations of the harmless variety. It’s mostly involved placing Timbers stickers and #RCTID (Rose City ’Til I Die) hashtags in Sounders-friendly bars and around Seattle landmarks. In one infamous episode, members managed to write “Go Timbers” in dust in a hard-to-reach nook of one of Century Link Field’s concourses, documenting the feat in photos shared online.

But they’re more than a group of soccer-loving pranksters, involving themselves in community service efforts like their Timbers Army brothers and sisters back in Portland. Pham, who oversees service projects for TA:CO, has even coordinated with Gorilla FC, a Sounders supporters’ group, on food bank drives.

Bullock, meanwhile, happens to work in Seattle’s Smith Tower, mere blocks from where Sounders fans congregate to march into the stadium. In fact, he can see Century Link from his desk; that proximity to Sounders support has made the Timbers’ 2015 MLS Cup win all the more delicious for him.

“Now, I have my scarf hanging in my office window,” Bullock says, laughing. “You can look up and see it from the street level. Probably someone’s looking up and that and going, ‘Why ... is that up there in Seattle’s most historic building?’”

The ultimate victory has indeed allowed Bullock—and the rest of his comrades in TA:CO--to be a little less covert about repping for the Rose City in the heart of the Emerald City.