Sex Criminals is a “mature readers only” caper comic whose first issue had six print runs. The newest creative team on Batgirl debuted with twice the sales of its previous installment and have held strong since. Lumberjanes is an original all-ages title whose first issue sales were comparable to those of licensed mainstays Conan the Barbarian and 24. What do these comics have in common, besides success? The support of the Valkyries, an international networking group exclusively for women who work in comic shops.

Founded in 2013 by shop employee and comics creator Kate Leth (Bravest Warriors, Edward Scissorhands) and a few others gathered from social media sites, the Valkyries have grown to a network of more than 300 women employed all over the world. The group’s purpose is to provide a social and professional network for women who work in comic shops, as they often find themselves a minority among male clerks and customers.

For many members, the sense of sorority has given them greater confidence in their work, and they have also pooled their knowledge in helping one another expand retail reach to previously underserved demographics. “Now I’m friends with women from other shops around town,” said Annie Bulloch, co-owner of 8th Dimension Comics & Games in Houston, who runs the Valkyries’ official Twitter account. “We can be competitors, or we can be a community, and I feel like we’ve chosen community.”

Community can be especially important for women within male-dominated geek spheres. In addition to feeling out of place because of their gender, new female readers often encounter a wall of prejudice. Many female comic readers have a story about an unfortunate incident that alienated them from a shop, if not multiple experiences at stores where female customers are brazenly not welcomed. To help change this, several Valkyrie stores have hosted successful “Ladies’ Nights” at their shops, where female customers gather to talk about comics, enjoy exclusive sales, and even meet female comics creators, all in a safe space. Women are the fastest-growing demographic among comics readers, so attracting them can be key to the success of a comics shop.

Just as importantly, the group is responsible for something that could be called “the Valkyrie bump.” Clerks’ comics recommendations—in the form of staff-picks sections and direct guidance to customers—can have a recognizable effect on sales.

When Batgirl’s hip new design included bright yellow Doc Martens, Valkyries were integral in sharing the news with fans and costumers. They made sure that if Doc Marten noticed the uptick in sales, they’d know it was because of Batgirl.

The effect on Sex Criminals has been even more pronounced. Time named it the best comic of 2013, the first trade paperback collection was #7 in 2014’s overall graphic novel sales, and the spin-off gift book Just the Tips was the third-bestselling graphic novel for December. The Valkyries’ support became especially visible when two members began a game of spoof images by re-staging a cover to Sex Criminals #1 on their Tumblr. The photo, after going mildly viral, culminated in a spoof of their spoof becoming a variant cover to issue #6.

For Lumberjanes #1, publisher Boom! Studios reached out directly to the Valkyries to organize “Lumber Day.” Participating stores pushed the title’s debut, while employees and fans pledged to wear flannel shirts and share Lumberjanes-related activities on social media. It’s remained one of Boom!’s bestselling titles ever since.

Though Lumberjanes fit the group’s interests, the Valkyries don’t exactly do requests. Cold calls from publishers are shared with the group, and if anything seems like a good match, “the promotion just sort of naturally happens by consensus—meaning it’s not a PR shtick, but genuine enthusiasm,” explained Ivy Noelle Weir, one of the group’s founding members, who now works as assistant manager of the Kennett Public Library in Kennett Square, Penn. Many Valkyrie-supported books came to their attention from one member or another simply sharing some news. “It’s just a way for women in this world of geek culture to say, ‘Yes, we love this, this is what we want to see more of!’” said Weir. The Valkyries represent not only the nature of internet marketing, where the hard-to-fake power of genuine consumer enthusiasm is a force to be reckoned with, but also the internet’s power to allow oft-overlooked demographics, such as women who buy comics, to communicate, organize, and grow into a consumer base that cannot be ignored.

The community’s most discussed book series include The Wicked and the Divine, Ms. Marvel, Thor, Bitch Planet, and Saga, all of which have had multiple printings. Even if one were to dismiss the Valkyrie bump as simply a correlation, it would be harder to deny that the organization collectively has an uncanny nose for successful titles, and that it might be best for publishers and fans (as well as retailers) to pay attention. You can find more information on the Valkyries at Bewarethevalkyries.com and on Facebook, Tumblr, and on Twitter at @LCSValkyries.