EL PASO — Luis Calvillo has an angel on his shoulder.

The tattoo covers his left arm, the archangel Michael wielding a sword over howling demons. But Mr. Calvillo, 33, believes it was an angel he could not see who kept him alive that day in August.

It was a Saturday morning outside a Walmart in El Paso, and the soccer team he leads was selling snacks to raise money for an out-of-state tournament. One moment he was chatting with a fellow coach; the next, a man was spraying the outside of the store with gunfire, and Mr. Calvillo was on the ground, blood pouring from his leg. Several soccer parents were also shot. His father, Jorge Calvillo García, was killed.

“I never thought about anyone else,” Mr. Calvillo said. “I was just thinking that it was going to be the last time that I was going to breathe. The last time.”

Only later did he have another thought: “My dad’s soul stayed there to protect me,” he said.

Mass shooting stories are usually told at funerals and candlelight vigils, cataloged by the number of dead left to bury when the gunfire stops. Surviving is a much longer story, often left unrecorded. There are the first chaotic minutes and hours in the paramedics’ van and the operating room. And there are the days and weeks of uncertain recovery that follow, the slow-motion coda of mass violence that unfolds painfully and privately. It took Mr. Calvillo nearly six weeks to be able to get a haircut, seven weeks to move without a walker for the first time.