Fern had initially considered a career in finance before pursuing acting. According to an interview with Anthem Magazine, he hated his life while working in finance. He said, "This is not what I want my life to be. But I'm here and I'm doing it and I'm trying to fit in." It was the Cate Blanchett-starring film duology Elizabeth and Elizabeth: The Golden Age that made him want to become an actor.[6]
In 2011, Fern played Romeo in Shakespeare WA's production of Romeo and Juliet, Lindsay in the Black Swan Theatre Company's Jandamarra, and the Earl of Southampton in the world premiere production of The Enchanters at the State Theatre of Western Australia.[11] He has appeared in a number of short films, including the Western Australian Screen Award-winning film Still Take You Home (2010) and The Last Time I Saw Richard (2014).
In 2014, Fern was the recipient of the annual Heath Ledger Scholarship by Australians in Film, an award aimed at financially and professionally supporting actors of Australian descent. This includes, besides a cash fund, a two-year scholarship at Los Angeles' Stella Adler Academy of Acting and Theatre and mentorship from the father of actor Heath Ledger.[12]
He appeared as Jim Mason in The Tribes of Palos Verdes and wrote, directed and starred in the short film Pisces opposite Keir Gilchrist in 2017.[13][6] In a Los Angeles Times sit-down interview, Fern had planned to take an 18-month hiatus from acting to focus on Pisces when Versace came along.[14]
In 2021, Fern portrayed Stan Vogel in American Horror Stories episode Feral, and Valiant Thor in American Horror Story, Double Feature: Death Valley. In 2022, he portrayed Thomas Browne in American Horror Stories episode Milkmaids. In 2022, Fern played a priest named Jacob in the film Father Stu.