Luis and Danny Moncada, better known as “the cousins” in AMC’s award-winning series "Breaking Bad" (2008) and its spinoff "Better Call Saul" (2015), return to primetime television this season as the menacing twin hitmen for the Salamanca cartel.

The Moncada brothers stalk silently through the third season of "Breaking Bad" and only have a couple lines — most of which are one word in Spanish — but are arguably the most memorable cartel killers in the show for their stoic and unwavering demeanor when committing brutal murders. Leonel (Danny) and Marco (Luis) come into the series with a mission to avenge the murder of their cousin Tuco (Raymond Cruz) and paying homage to Santa Muerte, the Mexican deity of death.

The cousins are introduced in Mexico, wearing sharkskin suits and pointed-toe cowboy boots with detailed silver skulls at the tips. They disguise themselves and make their way across the U.S. border in a hay truck, blending in with a dozen migrants on their way to Texas until the two are recognized by their boots as the infamous assassins.

The twins exchange a cold, knowing stare, then murder every person on the truck. They exit, casually, and Leonel lights a cigarette, then igniting the truck in a shattering explosion that engulfs the scenery in flames behind them. As they walk away, Marco and Leonel do not flinch, look back, or change their hardened facial expressions. Leonel takes a long drag of his cigarette.

It’s a scene the Moncada brothers — who performed the stunt without doubles or blast protection — remember well. It was Danny’s first-ever week of acting, Emmy award-winner Bryan Cranston was directing the scene, and the crew only had explosives for one take. It had to be perfect, natural, casual, like killing a dozen innocents then burning the bodies was “a walk in the park,” Cranston said to the brothers.

“This is nothing to you. This is like drinking coffee on a Saturday morning,” the more experienced Luis, who had been acting for seven years before joining the cast of "Breaking Bad", would tell Danny. “When you kill somebody, it’s nothing.”

Afterwards, Cranston, whom Danny had admired ever since watching the sitcom "Malcolm in the Middle" (2000) while he was in prison, came running and gave the brothers a hug, giddy about how perfect the shot was and questioning how they were able to not flinch. But for the Moncadas, it was easy. "Breaking Bad" was Danny’s first acting gig, but not his or Luis’ first up-close look at death, violence and destruction.

“I want to say our background is gangs, prison, change,” Luis said. “Then we started acting and we’ve been doing it ever since.”

“We learned with the punches, with the hard life,” Danny said. “We were able to turn that around and be ourselves.”

The Moncada brothers don’t shy away from sharing how their criminal history aids their portrayal of the villainous cousins.

Luis, who is three years older, and Danny first got involved in gang activity as teenagers in 1991, shortly after they immigrated to Los Angeles. In their native Honduras, they witnessed violence and survived a brutal machete attack as boys. When they started public school in the U.S., they were bullied for not knowing English, which led them to join gangs in order to stand up for themselves and find a place of belonging.

“I saw the respect they commanded. Guys that were in gangs, even if they didn’t speak English … I saw how people were fearful, they respected these guys,” Luis said. “And I got that. I said, 'I want some of that respect. I want people to look at me like that, not like I am nothing.'”

Danny said he followed in the footsteps of his older brother. Gangs were endemic in the Hollywood and Echo Park neighborhoods of LA, where they used to live. Luis said he advanced in the ranks with one gang and suffered the consequences, serving multiple sentences in county jail and then prison, with Danny not too far behind.

They spent a majority of their young adult life incarcerated. Danny missed the first seven years of his son’s life, serving time from when he was 19 until 26 years old. Ultimately, Luis spent six months in “the hole” — solitary confinement — where he said he came to the realization that he was throwing his life away. Danny came to the same realization soon after, and both of them developed a newfound respect for law enforcement and employment, which they now express to troubled youth.

“I’ll always remember the first time one of the officers shook my hand,” Luis said. “I got out of my car and never before that day, I had never went into a police station willingly... You keep growing, you get to thinking, this dude is a normal person, just like me. A normal person just doing his job. I was the one [messing] around, he was trying to stop me from doing it.”

Danny recalled, “I learned patience, I learned how to treat people the way I want to be treated. People think — 'oh, prison, they’re just a bunch of freaking animals' — but a lot of guys in there, they’re very very smart because they have so much time to think.”

When Luis got out of prison, he began working for a security and bodyguard company on Hollywood film sets. He has, he admits, an intimidating appearance — “come on, tattoos, bald head, gang member” — and one day a director approached him and asked if he wanted to be in a film. From there, he took minor roles like “gang-banger” and “cold-eyed killer.” Then came the casting call for the cousins.

Danny was not unioned and had never been in front of the camera before, but they auditioned anyway, performing two scenes and an improv in Spanish. Two days later, the brothers had roles in "Breaking Bad." Two weeks later, they were in New Mexico on set.

Director Vince Gilligan told Luis and Danny their roles would have very minimal dialogue. However, Danny said even though there weren’t lines to memorize, the cousins’ glances, expressions, body language and synchronization was even more crucial to perfect. The Moncadas had to develop their characters and instill fear in the audience without the help of a spoken storyline.

“You could say it was a little bit of luck, but I don’t think anybody else would’ve done it the way we portray ourselves in 'Breaking Bad,'” Danny said. “I don’t think a lot of people would’ve pulled it off the way we did because of the connection that we have. The way we look, the way we interacted with each other, I don’t know if anybody else would’ve been able to pull it off that way.”

Almost a decade after the first airing of "Breaking Bad" and a decade since Danny finished his last prison sentence, fans are still reeling from the brothers’ performance as they return in "Better Call Saul." They’ve gone on to have roles in films like "Fast & Furious" (2009), as well as "The Mule" with Clint Eastwood and "Kidding" with Jim Carrey, which have yet to be released. Sometimes the brothers audition for roles as a duo, and sometimes not.

They frequently give motivational talks to youth in the criminal justice system, and at Mixed Martial Arts (MMA) gyms, where they promote professional fighting as an outlet for aggression. They perform their own stunts whenever possible, and practice Muay Thai, boxing and other forms of MMA. They encourage kids to “get your butt in the gym, go punch the bag,” and look past drugs and gang activity, hoping to steer them towards the path they wish they had taken years ago in their own lives.

Luis has tattoos that say “f--- you” on his eyelids, but now both brothers excuse themselves before saying expletives. Luis and Danny have always considered themselves “goofballs,” and when they’re not filming as the silent-but-deadly cousins, they’re joking on set about farts. Even when they were wrapped up in the gang world, they said, they were always laughing, always positive and always together.

“All that bad energy that was there before, we channel that into and throw it on screen so we can really look like those guys, but we aren’t those guys in real life because if we were...we would not be free," Danny said. "It’s one of those things — you’ve got to get the demons that you had before, and use them in a positive way, which is the acting.”

To the dismay of their fans, who say the brothers’ performance scares them to death — in a good way — the Salamanca twins’ appearance in "Breaking Bad" is short-lived. They roll in with the goal of killing Walter White or “Heisenberg,” Cranston’s chemistry-teacher-turned-methamphetamine-cook character, but instead turn to Hank Schrader (Dean Norris), White’s DEA agent brother-in-law. The two go after Schrader in a strip mall parking lot.

Schrader crushes Leonel’s legs with his SUV, a stunt Danny performed himself, the car reversing toward him at over 20 mph. The crew made a hole in the trunk of the SUV and removed its bumper, so as the car hit, Danny, strapped to a harness, pulled his legs up into the back to avoid actual impact.

Then, Schrader has an epic gunfire exchange with the other twin, Marco, who pins the badly-injured DEA agent to the ground with no bullets left, except for one Marco had dropped earlier. But he hesitates to finish Schrader and says “No, muy fácil,” “Too easy,” leaving to grab his signature silver ax. He returns, but Schrader shoots Marco point-blank in the head. In real life, Luis has been shot before, which he recalled to aid his acting.

“A couple of times, getting shot at on set brought back memories or flashbacks of when I was getting shot at for real,” Luis said. “It made me feel a little bit uncomfortable.”

Dealing with memories of his own traumatic experiences is something that Danny has also had to confront in the course of his character’s story.

In the show, Schrader survives, as does Leonel, who has to have his shattered legs amputated in the hospital, bitter and vengeful after witnessing his brother’s death. His final scene alive is when he spots White, who he recognizes as their original target, outside his room. He rips a blanket away to expose the bandaged stumps that used to be his legs and leaps from the hospital bed. He crawls toward the door, leaving a trail of blood from his wounds. Leonel is enraged; the legless crawling is reminiscent of the cousins’ opening scene in Mexico, doing an army-style crawl to the shrine of Santa Muerte.

For this scene, Danny had to recreate a sensation of numbness in his legs, something he felt in his arms as a child in Honduras when he was attacked with a machete. He said his arms were sliced, down to the bone, and he couldn’t feel them from the elbow down. While filming, he had unpleasant flashbacks of the attack while recalling the physical feeling, but he channeled the painful memory into his character.

“That’s the beauty of it, you get to create these characters that are not real, but at the moment when you’re doing them, it looks very real,” Danny said. “And the lens captures that realness, that authenticity, that not too many people could bring. You use the bad things in your past, that you’ve gone through, and use it as good. Put it on screen.”

In AMC’s follow-up series "Better Call Saul," which details White’s lawyer Saul Goodman’s (Bob Odenkirk) life before "Breaking Bad," the cousins are younger and just as threatening to the Salamanca cartel’s opposition. The Moncadas make two brief appearances in the show’s second season, but are excited to be more involved in the fourth season, which began airing on Aug. 6.

The cousins will appear starting in the second episode on Aug. 13. Luis told AL DÍA News that the newest season is the best, most action-packed yet, with “unexpected alliances.” And with the Salamanca twins involved, there’s no doubt that things will get violent.

“It’s going to be ugly,” he said.