Boyd and Isaac were both students at Beacon Hills High School, though they did not actually meet each other until Season 2. Their shared anti-social lives and powerlessness were the exact reasons why the newly ascended Alpha Derek Hale was eager to recruit them and they agreed to be bitten and turned into Werewolves.
Both Isaac and Boyd immediately joined the newly rebuilt Hale Pack, becoming close friends with fellow Beta Erica Reyes, with whom Boyd seemed to form an especially close (and possibly romantic) bond. Derek picked Boyd to be his second-in-command because of his close-quarters combat abilities and heightened intelligence and helped Isaac be the first one to gain control during Full Moons. However, the threats of the numerous Argent Hunters led by Gerard Argent and the Kanima Jackson Whittemore eventually frightened Boyd and Erica so much that they decided to leave Beacon Hills to search for another pack somewhere safer and away from their hometown. Following their brief captivity in the Argents' mansion, the two ran back to the woods, only to run straight into the Alpha Pack and get captured by the malevolent Alphas.
Over the course of four months, Isaac did not stop searching for his packmates and finally found them being held captive inside the vault of an abandoned bank. Derek and Scott McCall broke into the vault to rescue Boyd as well as Derek's long-lost sister Cora Hale and ended up discovering Erica's dead body in a closet, as she had been killed by Kali several days ago while trying to fight the Alpha in order to escape from the vault.
Following Boyd's return to the fold, he and Isaac seemed to have grown much closer than ever, given their mutual desire to get revenge on the Alphas for killing Erica and for the terrible things that they had done to their friends and many other innocent people, human and supernatural alike. Despite Boyd remaining a loyal Beta to Derek, Isaac started to be drawn towards Scott, who was recently revealed to be a potential True Alpha, and his growing pack. After multiple of their attempts to take down the Alphas, Kali and twins Ethan and Aiden forced Derek to impale and kill Boyd, who had been weakened by a large electrical shock, with his claws, causing him to involuntarily take his power.
Isaac was one of the many to mourn Boyd's loss, which, in conjunction with his loss of faith toward Derek due to the latter's many mistakes as leader and Alpha, led him to defect from the Hale Pack entirely and pledge his loyalty to the official McCall Pack. Isaac never forgave the twins for their role in the deaths of Boyd and Erica as evidenced when he was the first one to straightly deny their entrance into the McCall Pack and during his Nogitsune-influenced possession, he attempted to burn them alive in retribution for the part that they played in the deaths of his close friends, though he was stopped at the last moment by Allison Argent and Kira Yukimura.