WARNING: The following contains spoilers for "Memento Mori," the sixth episode of The 100 Season 6, which premiered Tuesday on The CW.

Halfway through its sixth season, The 100 has proved it's still is capable of shocking viewers, as longtime characters remain relatively unpredictable. One of those who has experienced an emotional roller coaster this season is John Murphy, played by actor Richard Harmon. A major character since the inaugural season, Murphy has grown from a largely antagonistic opportunist to a key, trusted member of the last remnants of humanity, arriving at the start of Season 6 on board the Eligius IV to the distant world of Sanctum.

However, after enduring a near-death experience early in the season, Murphy spiraled into a alcohol-fueled binge, haunted by a hellish out-of-body vision he received before his resuscitation. Upon discovering the Primes leading the community on Sanctum had obtained immortality by transferring their consciousnesses into new host bodies, Murphy has seemingly betrayed his companions after secretly receiving a similar promise of immortality.

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In an exclusive interview with CBR, Harmon discussed Murphy's arc in Season 6, and how it has given him new depths to portray the character after six years.

"[I was] very, very glad when I found out," Harmon said, referring to learning about Murphy's storyline, which includes his betrayal of the others. In addition to the shocking development giving Harmon new, rewarding directions to the take the character, it also allowed him to work more closely with co-star Eliza Taylor. Her character, Clarke Griffin, had secretly been possessed by a Prime named Josephine, and prompted Murphy's betrayal with a promise of immortality in exchange for his cooperation.

"I love working with Eliza, which I don’t get to do often," he said. "I think we have good chemistry. I love that Murphy is a weak, broken man."

The 100 - Memento Mori

Despite the apparent betrayal of his longtime friends to the Primes, Murphy isn't undergoing a full-on, self-centered descent into villainy. In the latest episode, Murphy tearfully appealed to his friend Bellamy Blake to cooperate with the Primes. In addition to the potential for immortality, Murphy's efforts for the two factions to cooperate comes after enduring years of bloodshed back on Earth between rival groups of survivors that ultimately cost humanity the planet. Haunted by what he left behind, and his own near-death, Murphy sought solace in alcohol before siding with the Primes in a desperate bid to avoid violence on the new planet.

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"It’s not a full heel-turn, as they say in the wrestling parlance," Harmon said, "it’s been a ton of fun. I loved hard-drinking Murphy, and I suspect it’s not his last drink of the season. He’s my favorite character that I’ve played in my entire career. I can do a lot with him; make him as crazy as possible and have people just go ‘typical Murphy.’ What I love is that he’s not a hero and bogged down by morality, which I think is boring. He’s also not a bad buy but can shift his own morality to adapt and survive.”

The 100 - Mememto Mori

Murphy's conversation with Bellamy to convince his friend to cooperate with the Primes and take advantage of the possibilities on Sanctum has been one of the most emotional sequences in the season and one of Murphy's most impassioned scenes in the entire history of the show. Despite several cast members, including himself and co-star Bob Morley being sick during filming, the scene was a lot of fun for Harmon to play, exploring the depths of Murphy previously unseen. The tense conversation between the two characters was heartbreaking, with Murphy pleading, with tears in eyes, fully aware he's letting down Bellamy as he makes a desperate bid for peace.

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"[Bellamy’s] his brother," Harmon said. "He doesn’t want to be a bad guy, to betray his trust again even though he already has. In a lot of ways, Murphy’s relationship with Bellamy is a lot like my relationship with Bob [Morley]. That was a lot of fun to play even though we were sick and so was Eliza. It was just that point halfway through the season where everyone is sick on set and pounding DayQuil between takes.”

The 100 airs on The CW Tuesdays at 9 pm ET/PT. The series stars Eliza Taylor, Paige Turco, Marie Avgeropoulos, Bob Morley, Henry Ian Cusick, Lindsey Morgan, Richard Harmon and Tasya Teles.