Unhappy as an attorney, he teamed with Greg Ball, another newly-practicing lawyer, and together they created The Associates, a drama series based on their experiences as recent law school graduates.

[16] In 2020, it was announced Blackman signed a multi-year overall deal with Netflix and would continue to produce The Umbrella Academy in addition to other projects under the company name, Borderline Entertainment.

[17] In 2022, Blackman announced his newly renamed company, Irish Cowboy Productions, would be developing two new projects: Horizon Zero Dawn and Orbital.

[18] In June 2024, a report by Rolling Stone accused Blackman of creating a toxic working environment for writers and support staff.

An HR complaint against Blackman, dating back to January 2023, detailed his "long history of toxic, bullying, manipulative, and retaliatory behavior.