Sapper Morton was a Nexus-8 Replicant, and a combat medic, who hid in the outskirts of Greater Los Angeles as a protein farmer. He assisted in the birth and hiding of Rachael and Deckard's daughter prior to the events of Blade Runner 2049.
Events of 2048: Nowhere To Run
In 2048, Sapper went to Los Angeles to sell some of the leeches he had collected at a market. On his way, he was briefly harassed by some thugs but ignored them before meeting with a young homeless girl named Ella, who he was friendly with. Greeting her mother, he gave Ella a copy of the book The Power and the Glory, which he had enjoyed.
He then went to a stall, where the vendor would only buy his stock for $3000, $1000 less than he needed. Leaving the stall disappointed, he noticed the thugs from before trying to sexually assault Ella and her mother. Going into a rage, Sapper mercilessly beat up the thugs, killing some of them. Realizing what he had just done, Sapper quickly gathered his things and ran. Unfortunately, in his haste he forgot his identification papers, which a man who had been spying on him picked up. The man then went to the phone to report he found a "skinjob."
Events of Blade Runner 2049
An investigation later revealed Sapper's location and Officer K, a Nexus-9 Replicant employed as a Blade Runner for the LAPD, was dispatched in June of 2049 to "retire" him. Sapper had soup on the stove and was at work when he noticed K's squad car arrive. Knowing his time was up, Sapper calmly went into his home where he washed his hands as K watched. K learned a little about Sapper, who would only claim to be a farmer and offered K some garlic. K offered Sapper the option to surrender peacefully, but Sapper grabbed a pocketknife from his toolbelt and attacked K, sending him crashing through a wall and attempting to crush his neck, but the younger and more advanced replicant quickly incapacitated him before confirming Sapper's identity. Sapper managed to get up as K was retrieving his gun, and angrily called out K for killing his own kind. K claimed this was because the newer models did not run, but Sapper, thinking back to Deckard's child, replied that the truth was replicants like K had never seen a miracle. He took a step forward before K retired him with two shots to the chest.