IT’S A COLD WINTER NIGHT, and Karla Hernandez, a diminutive émigré from Mexico, is waiting in the dark. She’s lithe, even tiny, at 5-foot-1, with dark tresses she dyes in various, sometimes fanciful shades — scarlet red with blonde undertones this evening. She bangs her gloves together when she hears her name called. Her coaches gather round and they start the long walk to the cage.

Her friends and extended family cheer loudly over the blasting music — an obscure rock ballad most people don’t recognize — that fills the Humble Civic Center and envelopes the 500 or so people gathered to support their fighters. “My family comes to every fight, every sparring,” Hernandez says. “I’m a single mom, and I take my daughter to the gym with me.”

Hernandez is just one of the thousands of Houston’s dedicated and trained and mostly underground fighters. This invisible cadre cuts through every demographic category in the city; both genders, as well as every race, weight and height are represented. They form a burgeoning subculture with its own patterns, traditions, heroes and beliefs.

They gather in Katy, in The Woodlands, in Baytown, in League City, in Sugar Land, to fight and to train. They gather in warehouses and strip malls and converted service bays. There are the punchers and the grapplers, the tough guys and brainy fight philosophers, the weekend warriors and the budding professionals. They are a proselytizing army of combatants, and fighting is what defines them.

And their ranks are growing. New fighters are turning up in new training facilities every day. Jeff Messina, a Brazilian Jiu Jitsu black belt who owns a dojo near Downtown and another in Katy, began training about 20 years ago; he provides a metric for charting the growth of Houston’s fighting scene. “When I began training there was one black belt in Texas,” he says. “Now there are over 50 in Houston alone.”

And the nation’s fight promoters know about Houston’s thirst for combat. The premiere fighting league in Mixed Martial Arts, the UFC, will showcase several fights here Feb. 4, the night before Super Bowl Sunday, at the Toyota Center.

Back in Humble, the gate to the cage — an octagon-shaped space whose perimeters are marked with high chain-link fencing — closes behind Hernandez. The countless hours the 23-year-old Texas City resident spent training for this fight are behind her. This moment is all there is.

Before her, a tall, rangy Latina with lethal power in her hands and feet moves in. Hernandez raises her gloved fists and the distance between them closes. They are about to clash in the vicious style of unarmed combat that is MMA. It’s going to be brutal, and it’s going to be quick. Early in the first of what could be five five-minute rounds, Hernandez’s opponent launches a right leg kick, and it connects deep, just below Hernandez’s left ear. She begins to fall.

Upon the same December’s twilight, up in Spring, 26-year-old 5-foot-6 Cody Owens is leaving work. He has spent the day operating metal-cutting machinery, carving out tiny titanium parts for podiatrists to use for surgery. But to Owens, his day is just beginning. He recently turned pro as a MMA fighter, and it’s time to train.

He steps onto the thick wrestling mats at Team Tooke, where he’ll spend the next few hours honing his Brazilian Jiu Jitsu game and practicing his Muay Thai skills; these are the dominant sub-routines of MMA. His training space is a rectangular warehouse with heavy bags hanging from the ceiling, plus a square boxing ring and a small octagon. After wrestling — or “rolling,” as training fights are called in Brazilian Jiu Jitsu — with several other fighters, sweat trickles off his thick black beard. He will end his day bruised, exhausted and thrilled.

Combat sports of the sort Owens and Hernandez engage in can be broken into two constituent parts — striking and grappling. Or, put simply, the part where you get hit and the part where you get choked, respectively. Houston’s hundreds of fighting gyms and academies offer specialized training in both disciplines. While there are scores of fighting styles, the state-of-the-art training routines have coalesced around Brazilian Ju Jitzu for the grappling, and Muay Thai for the striking. Combine the two and you get Mixed Martial Arts, or MMA.

The blending of fighting styles highlights a unique sort of multiculturalism. When Hernandez and Owens rehearse the choreography they learn from their coaches, they are absorbing ancient knowledge tested through the centuries. These threads of know-how have passed down from both West and East.

From the West come boxing and wrestling, both of which were part of the original Olympic Games in ancient Greece. From the East comes the deep knowledge of martial arts traditions marrying physics and psychics — disciplines like Karate, Judo and Kung Fu. These rivers of fighting knowledge flow through the combat canyons of Brazil and Thailand, where they are further refined and codified into the national sports of Brazilian Jiu Jitsu and Muay Thai. In the end, this knowledge finds its way around the world through trainers like Houston’s Messina, and would-be fighters gather around them to take it all in.

The difference between a master Brazilian Ju Jitzu grappler like Messina and a beginner is often a matter of small adjustments, honed with much practice and patience in training. A master will defend with ease, and suddenly strike like a cobra and squeeze like a python. The fighter goes for the body’s weak intersections, like the elbows or neck. A Brazilian Jiu Jitsu contest will end in either submission or destruction.

But for Owens, the process of learning Brazilian Jiu Jitsu has, counterintuitively, led to the cultivation of compassion. “It makes you really give a sh*t about other people,” he says. “If you’re going to roll with someone, you’ll ask if they have any injuries you need to know about, and if you accidently do something to hurt them, you’ll stop and say, ‘Hey, sorry, man. Are you OK?’”

Is this why the Houston fight club is growing? Maybe because, for some, it’s at least as much about bonding with other athletes, as it is about beating their asses? Owens might just say yes. He came to the mats after his mother died. He was angry, looking for a fight, but he found compassion instead. He says the people made the difference.

In hushed tones, he talks about “physical touch” and the manifest good that comes from a sport that forces wildly divergent kinds of people to be in close contact with each other. On the mat, the races, the cultures, the backgrounds, the opinions on this or that, pass away, and there is just you and the other person.

“Sometimes, I roll with my eyes closed,” he says. “I want to really feel how people are moving.”

Sammy “The Bull” Mongonia works for a company that makes industrial valves, but he is also a Houston-based champion Muay Thai fighter. Muay Thai is fought in a square ring, like a traditional boxing match, but it allows for kicks as well as punches.

Mongonia is 30, with short-cropped brown hair and a bodybuilder’s physique. He came to the sport via religion; in his formative years, his parents were Christian missionaries who traveled throughout Asia with him and his brother. In Thailand, he saw Muay Thai practiced at a high level at its origin. Years later, his brother was looking for a way to lose some weight and so both boys took up Muay Thai, the sport they fondly associated with their time in Asia and their parents.

“I started training two days a week, and then it went to three days and then four days,” says Mongonia, “and I just kept going. Really, I never succeeded in other sports.”

Fighting uses every part of the body, and the training burns calories at a brisk clip. It is peak conditioning, and it shows. Fighters are sexy. But Mongonia swears his growing interest in the sport is about what’s on the inside: For him it’s a form of meditation. “When people ask me why I do this, all I can say is that, for those two or three hours I’m training, that’s all there is,” he says. “I don’t think of anything else.”

In the counterintuitive realm of the fighters, most cultivate a deep respect and concern for the wellbeing of others. Mongonia is highly skilled, but his fight journey has not elevated his blood lust. In fact, it has activated the opposite. “I got the nickname ‘The Bull’ because, when I first started, I would run across the ring and just start punching. And I’d get hit a lot, too. I don’t do that anymore,” he says. “I don’t like to hurt people.”

Mongonia credits much of his success to his coaching, and he’s most recently been fighting under the instruction of Mark Beecher, the head Muay Thai coach at Jeff Messina’s Revolution Dojo in Katy.

The thing about fight trainers is that to command respect, they have to fight or have fought. Fighter training is much more like working with a top chef or musician in that way. A respected football coach may not play or have ever played the game, but a fight coach has to be able to fight and win. If you can’t do, you can’t teach.

Mark “The Hyena” Beecher is a 46-year-old heavily tattooed former champion who can teach. In the 10 years he fought professionally, he accumulated a Muay Thai record of 45-16. Like so many others, he first came in contact with the sport by chance when he was a Navy brat growing up in Hawaii. “Hawaii is a very diverse culture and there are a lot of Asians there, so they used to have Muay Thai events on TV,” he recalls. “I loved it as soon as I saw it. I didn’t know what it was, but I knew I loved it.”

A relative newcomer to the Houston fight scene, Beecher sees the intense and growing interest in fighting here. “It’s not as big as in Las Vegas, where everyone is a fighter,” he says of Houston, “but it’s big.” He trains by example and moves with the skill of someone who’s practiced a move hundreds of thousands of times. He possesses a certain threatening grace. And while most fighters can blend in to a crowd if they chose, Beecher cannot. He just seems like a fighter.

“This area right here,” he says to his class as he waves his arms in an arc around his body, “this is my house. This is my space. If I didn’t invite you into my house, and you come in anyway, you have to get hit.”

He can read a fighter, tell what they want to achieve and what it will take to get them there, and if he smells bad intention, he’s out. “I don’t train thugs,” he says, “but a lot of guys will stop being a thug when they get their ass beat by a regular Joe.” And he makes sure his fighters know the truth about fame and fortune. “Being a fighter is like being in a rock band. There’s money at the top, but mostly, you do it because you want to.”

You do it, Beecher adds, because it makes you powerful. And not because of the punches you throw, but rather because of the punches you take. “When you fight, and you realize that you’re not made of glass, it will change your life,” he says. “You hold yourself different.”

Back in Humble, Karla Hernandez crashes to the mat, lifelessly it appears. Her family gasps. The force of her opponent’s kick transfers through her head and for a moment she has not only fallen to the mat but also into a dangerous wrinkle in time, a defenseless and terrifying moment for any MMA fighter. Within the rules, if a fighter falls, her adversary can pounce and continue the assault, often with blows to the face, unless the referee determines the downed fighter is unable to defend and stops the fight.

If Hernandez is able to think at all, her mind might take her back to how she got started fighting in the first place. Like Mongonia, her fight journey started with a sibling who wanted to begin boxing as a way to lose weight. Hernandez didn’t want her sister to go to the gym alone, so she tagged along.

In just months, the outward change was easy to see. After giving birth to her daughter, Hernandez had put on a lot of weight. When the gloves went on, the weight came off, and she slid from a high of 170 pounds to a fighting weight of 115. But the invisible changes were even more profound; Hernandez was becoming a competitor. Her coach entered her in a fight, and she won. The positive-feedback loop began — train, fight, win. She fought and won, fought and won, fought and won. And she was hooked.

Tonight, however, she loses. The ref lays his own body across her, protecting her from additional punishment. Hernandez’s opponent, 20-year-old Itzel Esquivel, raises her fists in victory.

After the loss, Hernandez is quiet. She communicates only that she is uninjured, and dealing with the emotions. And that she’s ready to continue her training. She’s still a fighter.

“I get messages from my high school friends, from my Mom’s friends, saying they are proud of me and stuff,” she says. “They see the sacrifices I make. They see everything. And people say, ‘Oh, Karla, look at you, you’re pursuing your dreams.’ People say I’m inspiring, and I never thought I’d hear that.”