In the 1960s-set saga, David stars as Sam Hodiak, a cop going undercover to take down real-life serial killer Charles Manson (played by Game of Thrones' Gethin Anthony) and his devotees.
TVLine announces that Gaius will star as Bunchy Carter, "a former gang-banger who is now a fanatical Nation of Islam adherent whose hatred of the white man is evident. He preaches his isolationist doctrine in the inner city — and those who don't adhere to his teachings are routinely threatened and intimidated."
Furthermore, Bunchy and Hodiak are old nemeses, and when their paths cross again, Hodiak forces Bunchy's "cooperation" by any means necessary.
Not only is the 31-year-old actor returning to his NBC roots, he's also reuniting with a fellow Friday Night Lights co-star, Grey Damon, who will also appear in Aquarius.
We'll miss 'em both on Grey's, but we're always happy to see our departed TV docs get more work.