Efraín has hinted he was a priest in Tijuana, Baja California, prior to the beginning of the apocalypse.
Sometime after the beginning of the apocalypse, Efraín became a vagabond who traverses the streets of Tijuana caring for those in need. At some point after Dante's take over of the Gonzalez Dam, he and Lola, the head of the municipal water utility, set up a secret arrangement for water to be supplied to a tucked away fountain every Tuesday at 5 PM. Efraín distributes the contraband water to the needy in an old rickshaw, notifying survivors of his presence with a recording that repeats "agua, agua, agua."
After Daniel passes out, he's awakened and pulled out from under the car by Efraín who sees Daniel's charred legs and warns him he'll die if he doesn't get help -- and water. Efraín leads Daniel to a shed with a dry water fountain. Daniel is skeptical that the water will come, but at exactly 5 p.m., water begins to flow. Daniel laps it up thirstily, and Efraín fills his jugs while explaining that water miraculously flows from the fountain at 5 p.m. every Tuesday. Incredulous, Daniel wonders who this man in front of him really is. Efraín, revealing his penchant for humor, provides a little comic relief: "I'm the fifth Beatle, and you?" Efraín then loads Daniel into a rickshaw and peddles through the zombie-filled town, expertly dodging the Infected along the way. Efraín delivers some water to a family. They scoot out of sight as a vehicle of armed men -- whom we later learn are ruled by a cruel big shot named Dante, who controls the water supply in this godforsaken place. Daniel fades in and out of consciousness as Efraín and his friend Lola debate how to treat Daniel's infected leg.
When he awakens, Lola is pulling out a knife. He screams in pain as she scrapes off the charred skin with a blade. Eventually, he feels good enough to bond with Efraín and share some whiskey with his new friend. A trained barber, he gifts the homeless man with a needed haircut. Efraín is captured by Dante's henchman and brought back to the dam to be tortured for information as to who has been secretly sending water to the fountain. Daniel tells Efraín if he confesses both he and Lola will be killed, but if he stays silent then Daniel will kill Efraín quickly out of mercy. As Daniel tortures Efraín on Dante’s command, he asks Efraín for forgiveness. Efraín responds: “Again?” Lola confesses to save Efraín and the two along with Victor, Pablito and Everardo are taken to the edge of the dam. Dante plans to toss all five off the dam to make an example of those who steal water from him. After Pablito is thrown off the dam to his death Daniel intervenes by killing Othón, J.C. and Dante, thus freeing Efraín and the others.
At the dam, Lola mobilizes her group to distribute water on the street. Daniel and Efrain urge her to stay behind for her safety, but she insists on joining them. Lola and Efrain distribute water to a crowd. A man accuses them of controlling the dam for personal gain. Daniel rushes Lola to the truck as the crowd turns on them and attacks. They drive off.
Efrain, Daniel and an injured Everado race down the road in a water tanker with an angry mob in pursuit. Daniel attempts to shoot at the mob, but Efrain orders him to stop. Daniel’s group reaches the dam and shuts the gate behind them. Efrain admonishes Daniel for shooting at the crowd. Daniel sees someone emerging from a pipe: It’s Strand, Madison and Walker. Madison tells Daniel that Ofelia is alive and that Walker saved her in the desert. She tells them they’ve come for water.
Efrain and Daniel bring Madison and her group to see Lola. The gang waits outside and sees an argument ensue through the glass. Moments later, Daniel invites them inside. Lola offers Madison a seat while the men in the room remain standing. "Our camp is running out of water but we have resources that can benefit you," she says. Efrain tells Lola they don't need anything from them, but she cuts him off. Lola, however, is completely disinterested. "We have no water to spare," she tells Madison. Madison stands up to tell Lola of the threats she will be facing. Lola insists, there is nothing left to discuss. She offers refuge for the night, but leave in the morning.
Strand offers his help as Efrain treat Everado’s wound. He doesn't trust Strand, though, because Daniel calls him "the snake." Strand starts getting to know them, though. They debate different outlooks of the world. Strand rules, "Uneasy lays the head that wears the crown." Efrain criticizes Daniel for attacking the people, who he believes are merely thirsty and scared. He rejects Daniel’s belief that people are plotting to overtake the dam and maintains that Lola should release the water to everyone.
Efraín, Lola, Daniel, Madison and Strand are warned by Troy and Nick that the Proctors are going to attack the dam. Daniel reveals there are three entry ways. They come up with a plan to defend the dam which calls for C4 and teamwork. Later, The Proctors infiltrate the dam through the unguarded tunnels. Daniel’s men ambush the Proctors. Gunfire breaks out, Efrain is shot and killed by the Proctors.
Efraín's corpse is discovered by Lola in her office. Deeply saddened by the death of her close friend, she is instilled with a desire for revenge against the Proctors, only to be killed by Proctor John.
While Efrain was looking at his papers. He didn't notice the fighting that is happening at the dam, this caused him to be clear target after being spotted by proctor gang members, causing him to be shot to death.
This list shows the victims that Efraín has killed:
Efraín saves Daniel's life on the streets of Tijuana and nurses him back to health. They become friends and bond when Daniel gives Efraín a much-needed haircut. Daniel repeatedly asks Efraín, a priest, for forgiveness, which Efraín is unable to provide. Daniel ultimately saves Efraín's life by killing Dante and his henchman before they could throw him off the Gonzalez Dam.
Lola and Efraín are close friends and work together to provide water to the needy behind Dante's back. Lola deeply cares about Efraín and confesses to routing water to the fountain to stop his torture at Daniel's hands.