Boris rose in standing among his peers following Outbreak Day with his archery talents, killing many clickers with ease. Sofia considered him the best clicker killer in the QZ. In time, he became the community's leader.
After the Washington Liberation Front overthrew FEDRA and the military, only to become the city's new oppressors, his best friend Uli tried to convince him to stand up against their order to relocate to SoundView Stadium with the rest of Seattle's surviving population, believing that Boris could convince their neighbors to resist the WLF. His neighbor Yolanda, sensing trouble, asked Boris to look after her dog Alfie and left the city before things became worse.
Fighting the WLF
However, tragedy struck when Sofia, while making protest art, was caught and gunned down by a WLF patrol, breaking and enraging Boris, much to the horror of his friends. Many people, including the Brandmans, decided to comply with the WLF's orders out of fear for their families. Some, like Dale, also wanted to join the WLF to have access to their medical supplies.
The lack of communal support angered Boris, who wanted to wage a war against the WLF, and led to him ambushing and killing an entire patrol, leaving the message "COME GET ME" on the side of their jeep. This caused his remaining neighbors, Uli and X included, to conspire to turn Boris in to save themselves.
However, Boris learned of this and, embittered by his friends' betrayal, drugged them unconscious and dragged them into a garage full of spores. A now-infected Uli woke up and, after a brief struggle, bit Boris before being sealed in the garage. Boris wrote a final note to Yolanda, apologizing to her for not being able to take care of Alfie, writing that he could already feel himself losing his mind, and said that he hoped that his former friends' final lucid thoughts would be of him as they turned into runners. He then locked himself in a garage and transformed into an infected, eventually becoming a stalker.
Events of The Last of Us Part II and death
While searching for Tommy Miller, Ellie found various notes addressed to Boris, in addition to his final confession, eventually encountering his infected self. After a brutal fight, she managed to kill him, enabling her to claim the bow still slung on his back.