Howard Hargrave is a private intelligence contractor. He was once married to Susan Hargrave and is the biological father of Tom Keen. Howard allies himself with Tom and manipulates him into believing that Susan Hargrave tried to have him killed. Tom joins Halcyon briefly along with Mr. Solomon and hired mercenary Nez Rowan. After numerous missions together, Tom continues to get information from Howard about his mother. This leads to a deadly showdown which ends with Susan Hargrave being arrested and taken to prison after she is framed by Howard for making a supercomputer. It is revealed at the end of the first season that Howard and his friend, Whitehall, have been working together to build a supercomputer. Due to the Blacklist Redemption being cancelled, Susan Hargrave appeared in "Ruin". She reveals to Elizabeth Keen that Tom went to trial and testified.
- The name Halcyon Aegis is ironic since it literally translates to “peaceful shield” and their operations create controlled chaos.