Because our protagonists have fled to Hawaii after a military coup goes down, it’s likely that the group is being tracked and studied by experts in all fields, from the Department of Defense to…geneticists.
So even if he isn’t a creator figure, Henry Ian Cusick could easily be the big villain for the Inhumans, as Iwan Rheon’s antagonistic Maximus likely won’t be an overarching baddie for the series.
Given the Royal Family of Inhumans — as led by Anson Mount’s largely silent leader Black Bolt — came into existence due to genetic experiments performed on humans.
In the comics, the genetics work was started by the Kree, but it’s unclear if the TV show will follow in this direction, and it’s plausible that Declan could have something to do with it.