[5] He attended school in County Kildare, where he also made extra money helping farmers deliver lambs; in one classroom, three separate grades were being taught by one teacher, which he described as "very Little House on the Prairie-esque".

His first job in Los Angeles was at the now defunct Storyopolis, a children's book store/art gallery, in Studio City, where he worked with writer Blake Harris.

[7] Prior to selling his first spec screenplay, Duffield was a temporary employee at the Lucky Brand Jeans factory in nearby Vernon, California.

[1] The story is partially based on his personal experience with his friends' weddings and a slew of failed relationships.

[15] The film underwent some rewrites by Matthew Robinson and was renamed Love and Monsters before being released in October 2020.

[16][17] Duffield's first writing assignment was for the film adaptation of the second book in the Divergent trilogy, Insurgent (2015), in 2013.