THE DEVIL WATCHER'S THEME:
The Devil Watcher is an unidentified and elusive hacker, blackmailer and cyberterrorist who serves as the main antagonist of season 1 of Ben 10: Heroes of Evolution.
The Devil Watcher has yet to make a physical appearance in the series, with his only portrayal being through his electronically deepened and distorted voice, heard on various communications channels including cellphones and intercoms. The Watcher is shown and suggested to have a large network of operatives and assassins who act on his orders, having been recruited through various measures ranging from blackmail and other forms of coercion, to simple persuasion or bribery - some operatives join at their own free will. The Watcher's current plan is unclear, but it is suggested that it is very large-scale and he claims to have visceral repercussions.
Ben Tennyson and his gang first learn of (and come in contact with) the Devil Watcher in "Brothers", after hearing from a defeated Krill and Wyatt Herman their story of their shift from Plumbers to private assassins when the Watcher blackmailed them in 2012 with their parents' safety. After hearing their story, Ben, impulsively and accidentally, texts the Watcher with a threat, prompting the hacker to reply with a recently-taken picture of the brothers' captured parents, coercing the two to consume cyanide and die. Max Tennyson, the former mentor to Krill and Wyatt, arrives upon being alerted to the situation much earlier and is horrified to find the two dead. Back at the Plumber HQ, the Watcher appears reasonable in that he safely returns an unharmed but traumatized Angela and Tundra Herman to the base, with a taunting note warning Max to stay prepared upon the Watcher's return. This fuels Max's vengeful compulsions against the Devil Watcher.
At the end of the "The Legacy Artifact", the Watcher is revealed to have some sort of connection with Forever King Phil Stephens, whose identity the team realized elsewhere but were sent to the wrong location while Stephens murdered Rick Thomas and stole the Everstone. A band of guerrillas destroys the Everstone along with Stephens and his plane before they themselves are gunned down by one of the Watcher's assassins. Aware of a rival group at hand but skeptical of Stephen's commitment to whatever deal he's made with them, the Watcher orders his man "back to base", which suggests the existence some sort of temporary headquarters or meeting spot.
The case in "Authorities" has indirect connections to the Devil Watcher in that Ssserpent, a known enemy of Ben's and an estranged accomplice of the Watcher's, inflates the manufacturing of "Demon's Blood" - a corrosive chemical previously used by Krill and Wyatt - by numerous drug cartels. Prior to the events of the episode, the Watcher had come to neglect the Demon's Blood as a somewhat effective but non-integral weapon not worth putting into the forefront of his plan - Ssserpent's disagreement and subsequent defiance forces the Watcher to pick apart the cartels and lead Ssserpent into a trap, to eliminate loose ends. Ssserpent is ultimately consumed by a Null Void projector the Watcher hid inside the headquarters of the main drug company.
The Devil Watcher is most prominently featured in "The Number Game", where he acts on his warning he gave to Max and digitally takes over the Plumber HQ in space, hacking its servers and locking it down. Max consults Ben and the team on the case to spread closure on the Watcher, and the Plumbers (including newly-arrived Magister Sylax Newell) are all informed of a mole in the agency, working actively within the premises to engineer the attacks on them. He sends them three sets of numbers, two of which map out to space coordinates housing missing Plumbers whose ID's match the number, and the third being hidden by an elusive encryption.
The first part of the mission proves disastrous, with famed Plumber elite Brian Reed betraying his team and taking them hostage while the second team stumbles on a cooled room housing mutilated Plumber carcasses. Both compounds explode before Ben can save the teams, injuring him. The third set of coordinates, which Gwen and Kevin go out into the field to investigate, is a cloaked warship possibly housing hundreds of other Plumbers - a hospitalized Ben, with the help of Eunice, secretly spies on the mission as well as Newell, cross-referencing the man's behavior and history with observations he had prepared earlier out of suspicion; concluding that Newell is the mole, Ben escapes his hospital cell and attacks the Magister, putting him into a secluded and brutal interrogation with Max watching.
Despite the coincidental evidence, everyone soon comes to realize that the mole is not Newell but Thomas Bridges, the head of the tech team who previously played an instrumental role in the case. Thomas, after murdering three other techs who witnessed his exposure, lures Max into the damaged command deck and later shoots him, prompting Ben to attack him and nearly kill him until an army of elites surrounds the room. Thomas, knowing he will die, recites a poem symbolizing the Devil Watcher, before revealing the name of his boss and killing Newell with a Demon's Blood-laced bullet. The elites retaliate with extreme force and kill Thomas with a barrage of bullets.
This is followed by the Watcher returning to the intercom systems. He and Ben have a cryptic and playful chat in which the Watcher reveals the numbers to be included in a grid of other numbers, which then animate and recolor into the image of some kind of posh living room. The Watcher shows Max his burning office, and announces to the Plumbers that their role in the mission has come to an end, though he claims Max's hasn't and his death is something more "grand". He does acknowledge that Ben's consequences for torturing Newell are inevitable, though he is eager for continuing his "game". Ben shows his anger and retaliation to be a façade hiding his true eagerness to continue sparring with the Watcher - he asks when they start.
Personality and Methods
Despite minimal background info being disclosed on who the Devil Watcher is, his personality, mindsets and methods have been displayed both by the way he operates and the way he expresses himself.
The Watcher is presented and portrayed as extremely cold, ruthless and swift, coming across as a sociopath who puts his intelligence to a purely strategic use that is regardless to the people involved or the outside casualties. However, this is not without a great deal of theatrics and a capability to accommodate differing opinions with egomaniacal justifications. The Watcher likes to be cryptic and treats almost everything like a game, always providing clues and acting on exactly what he has in mind for a plan. He almost seems to be directing a play or feature with a script he follows by forcing his "actors" down a specific course. This makes him unhindered and dismissive to what others may perceive as a potential hardship, as the Watcher is an opportunist with a plan in mind for everything. This makes him exceptionally confident and certain of a planned outcome.
The Watcher uses his power to justify what others may see as a vulnerability - from what ha been shown so far, his plans seem to succeed despite what course they take, perhaps due to his meticulous and elaborate planning of everything. Using this as the basis to prove his claims of power, what people call his "cowardice" to remain in secrecy and "delusions" of his expansive plans are all brushed off by him as mere factors to the bigger picture, which are misinterpreted easily and typically.