Null Squad

Null Squad was a covert operations unit in the N7 Special Ops tasked with hunting down other squads that deserted, and recovering stolen war assets. Formed personally by Clayton Travers, Null operated solely at the discretion of N7's Command Cell. Made up entirely of ex-Cerberus defectors, each was chosen for unwavering obedience and superlative combat ability. Identified only by codenames to prevent association with Alliance or Cerberus dossiers, it was deemed wiser to keep Null's existence a secret than use them as a threat to deter deserters, as all squads were made up of more than capable combatants, and it could have led to the squad being compromised. Dispatched from one of N7's few Normandy-class frigates, Knife in the Back (formerly the SSV Dunkirk), the squad was ruthless in carrying out their assignments, leaving no member of a rogue team alive. While no evidence of them was ever uncovered, the frequency of desertion became drastically low after deserters earned a reputation for mysteriously disappearing.

Null One: Smokestack
Null Squad's team leader uses few verbal cues in the field, and even less off the battlefield. Only in private mission briefings with his team does he ever speak at length, and he commands the utmost obedience and respect from its members. It is earned by the extreme efficiency and flawless execution of his squad tactics. Lethal with all manner of small arms and close combat techniques, Smokestack's time with Cerberus has conditioned him to kill aliens and humans alike without remorse. While not sadistic or unnecessarily cruel towards his marks, he shows no mercy in hunting them down.

Null Two: Static
The squad's surveillance expert is speculated to have been part of the Nemesis program before deserting Cerberus. While a methodical sniper, Static's primary gifts lie in her ability to track and predict target movements, invaluable in preventing enemy escapes and reacting quickly to unforeseen obstacles. Though perhaps not as ruthless as the rest of Null Squad on her own, she defers to Smokestack's judgement at almost all times, the last survivor of the group that fled the Illusive Man with him. On or off the field, Static demonstrates a complete lack of emotion and machine-like precision some find unnerving.

Null Three: Tripwire
A demolitions expert loosely matching the profile of a prominent Cerberus terrorist, Tripwire has no qualms killing who he's told. He is extremely thorough with any assigned task, making absolutely sure his ordnance does the job without unpredictable excess damage. Despite the disciplined organization he applies to his work, Tripwire is extremely cynical and unruly. He resents most other species, but generally gets along with his squadmates and follows Smokestack unquestioningly, respecting his team leader's decisions even when they conflict with personal feeling.

Null Four: Tap
One of the defectors from Project Phoenix, Tap chose to join Null Squad over staying with his own when given the choice. His slightest effort of biotic energy is always exact and deliberate, never wasting any energy. Although his first moves in a fight are subtle, once Tap is confident in finding a weak point he strikes with the concentrated power of an enhanced biotic warrior, crippling large targets and laying low crowds of those less well defended. Constantly seeking a way to make himself even stronger, it is his lust for power that keeps him loyal to N7, and his respect for Smokestack's skill that keeps him loyal to Null Squad.

Notes and References

 * Kind of seems like cheating to make a unit like this, but perhaps using them in a story will justify their existence. Sometime in the afterwar, Travers, who becomes corrupt, may order them to go after some familiar good guys. The black ops team is then killed after the good guys realize they're dangerous.