Israfil was born Tal, of the Sun Dogs: a post-War wasteland tribe located in the American southwest. Little is known of the Sun Dogs, other than they were routinely raided by the neighbouring Blackfoots, an almalgamation of raiders, ranchers, and displaced locals, who augmented their numbers by preying on other, smaller tribes. The Blackfoots eventually formed into a totalitarian army, "Caesar's Legion", which would completely subsume every other tribe in the American southwest within a matter of years. Led by a Followers of the Apocalypse humanitarian, Edward Sallow (otherwise known as Caesar) and his right hand, Mormon missionary Joshua Graham, the newly-formed Legion subjugated the Sun Dogs when Israfil was only ten years old. Any boys of military age were taken to be incorporated into the Legion's slave army, with the tribe's women being taken to serve as healers, breeders, and midwives.
Despite his young age at the time, Israfil was given the "true" name of Tiberius, and formally inducted into Caesar's Legion. Following completion of his training he joined the Sixteenth contubernia, who served as speculatores, or scouts, for the Legion's forward advance into Arizona and southern Utah. Israfil proved particularly loyal to the Legion and to his contubernia, soon establishing himself as a diligent and devoted soldier in Caesar's army. Israfil's commanders noted early on that he displayed a particularly tenacious will to live: he had a tendency to fight tooth and nail when sufficiently cornered, whilst as an adult there was seemingly nobody that he wouldn't step over to ensure his own safety.
By 2274 the Sixteenth contubernia had pushed into Rockland, Idaho, making it the most northernmost point of the Legion's attempted expansion. Having met with heavy resistance at the town of Idaho Falls, the contubernia was forced to retreat back to the Utah border. Coming on the heels of the 2271 Ranger Unification Treaty, ceding any of the Legion's northern foothold would have been an unconscionable loss. The Sixteenth were told to prepare for a second attempt to push past the Snake River, despite suffering heavy casualties in their initial, failed assault. In retaliation, the speculatores revolted against their leadership. Israfil was put to the cross alongside the Sixteenth's two decani, as well as two other speculatores who had opposed the coup attempt.
Two days later, a group of Mormons from nearby Ogden came across the grisly scene overlooking the town of Providence. They were able to recover Israfil, who was near death, and bring him back with them. In the months that followed, Israfil slowly recuperated from his ordeal whilst absorbing the New Canaanite's teachings. It was during this time that he took his final name, Israfil Nahem.
Israfil eventually left New Canaan and returned west, where he took up employment as a Courier with the Mojave Express. Quickly earning a reputation for taking on the jobs that nobody else would, Israfil regularly ran packages as far as Washington in the north and down to Baja California in the southwest - although he refused to deliver to the Utah-Idaho border, or any other state where the Legion were known to operate, hoping to conceal his survival from them for as long as possible. Whilst on one such delivery between California and the New Vegas strip, Israfil was ambushed by a group of Khans just outside the town of Goodsprings, who shot Israfil and dumped his body in a shallow grave.
He was subsequently found and nursed back to health by the people of Goodsprings, until he was well enough to make his way back to the Mojave Express. En-route, Israfil passed through the town of Nipton, which was in the process of being sacked by Legion spies. Despite his best efforts to go unnoticed, Israfil was found and recognized by the leader of the frumentarii, Vulpes Inculta. As they prepared to put him to the cross for a second and final time, Israfil mentioned something that piqued Inculta's interest regarding his recent assault in Goodsprings. He ordered Israfil cut down, and instead struck a deal with him: he would keep news of Israfil's survival a secret, in return for the package Israfil had been carrying. With no other option than to play along, Israfil agreed.
Israfil eventually tracked the missing package to New Vegas and the Chairmen, a former warrior-tribe now under the yoke of the mysterious Mr. House. His journey across the Mojave had amassed allies to his cause, including a former First Recon sniper with a murderous hatred of the Legion, and now he faces having to betray them all and doom the Mojave in order to secure his own safety. Tiberius, of Caesar's Legion, would've delivered the package to Cottonwood Cove without a second thought. It remains to be seen if Israfil Nahem is the same man.
A note on Ships: Due to the Legion's policies on homosexuality, Israfil is a gay man who didn't come to terms with his sexuality until he was an adult - and even then, he is essentially closeted due to years of internalizing homophobic rhetoric. His first experience with same-sex attraction that didn't carry the threat of death was probably with the New Canaanites, and like... they're Mormons. It's possible that Arcade is the first time Israfil has not only recognized another man's attraction towards him, but started to reciprocate it. This is, of course, complicated by his initial belief that Arcade is a Legion spy, as well as the fact that he himself is a secret Legion spy, and the knowledge that Inculta won't hesitate to weaponize his love for Arcade against him. I think Israfil and Arcade have a happy ending, eventually, but it takes a hell of a long time for them to get there - possibly even long after the events of New Vegas.