Doctor Who Flux: 10 Huge Questions After Once, Upon Time
4. Who Is The Grand Serpent?

In truth, Craig Parkinson, best known for being the first H
and the Caddie in Line of Duty (were the slanted H symbols decorating the
Sontaran ships an in-joke?) didn’t quite live up to his more grandiose title,
but we are assured there is much more to come. Is the intergalactic dictator
just fond of camp villain names, or does his title suggest a more overarching
function as the story progresses?
In a trailer for the series, Parkinson can be spotted dressed in period clothes outside an English stately manor, so somehow he has been transported across space and time. It could be the Weeping Angels, or more likely, the Ravagers using him just like Diane, but don’t rule out the possibility of the Grand Serpent travelling in the TARDIS especially as the Doctor has agreed to help Vinder find Bel.
Parkinson is too recognisable an actor to play a minor supporting role, so there’s always the chance he could be a time traveller, perhaps even another Time Lord up to no good and hidden in plain sight. The mythological associations of the name might also be signifying a more sinister part. Let’s not forget the Master once took on a snake-like appearance (The TV Movie).
The redemption that Vinder is seeking isn’t for his whistleblowing. Even then, he is still living with the unresolved guilt of having carried out the Grand Serpent’s orders. He’ll have unfinished business with the Grand Serpent, who so far has been getting away with his crimes.