One of those moods.
Created for an alternate universe Matrix RP (and dragon adoptable setting) where, from memory, Neo never actually came to be, Core was another in a long line of character designs that I've become fond of: the robot, analytical and logical and with little interest in human methods and emotions. Invented by the machines in an attempt to better confound their human opposition, he was seven feet and two inches tall of black metal and featureless face with glowing green eyes. Which was then promptly wrapped in albino skin with white hair, an equally white trenchcoat, and given glasses to hide his glowing pupils. If the Agents were Supermen within the Matrix, the prototype Enforcer-class Core was the equivalent of the Terminator. Massively intimidating, immune to bullets, and a borderline broken ability to as per his classificiation Enforce the rules of the Matrix on his surroundings. That meant no time-bending shenanigans, no super-powered kung-fu (regular kung-fu was just fine), no impressive feats of leaping, wall-running, and so on. It was the goal of the machines, after the test run of the prototype, to deploy them in concert with Agents to ensure that no human ever got away again. And as per my favorite cliche with these machines, it all went bloody wrong for one very simple reason. That being of course the fact that AI is a crapshoot even for other AI, and the evils of free will.
Core had a secondary function, to try and infilitrate with the humans. Like the famous quote about the T-600 Terminator having rubber skin and being easy to spot, this was inevitably doomed to failure because no human (Matrix or in the real), would believe a buff albino human was totally on the level. However, in order to be able to do this he was given a surprising amount of latitude with his thought processes, able to logically think on his feet, deduce things, and come to a reasonable solution as opposed to just blindly following orders. That, along with the side-effect that his Enforcement ability didn't take sides (Agents were just as fucked in the supernatural department as humans were), gradually led him to fall in line with the humans rather than his Agent handlers - and when you're brought down to normal, there's not much you can do against a seven foot robot facethrowing you out a window or elbowslamming you through a wall. At first it was assumed the infiltration was going well, and then naturally, he turned against them more openly by not... you know, turning on the allies he'd found aboard the... Corinthian I think it was. However, from an external perspective this made things difficult as having something that could just knock off Agents easily was rather overpowered. It never really got very far that I remember, but I did come up with something regardless.
As an ex-Machine (in terms of allegiance, not so much his physical makeup), the Enforcer was a great big honking red mark in the system. A method of last resort as it were, meant to bust everyone else out of the fire. The moment he used his own mounting plug (concealed in one arm, its intended use was 'interface with human brain and rape for information') to log-in to the Matrix and make the save, it would throw up a great big red flag showing exactly where the Corinthian or whatever ship he happened to be on at the time was hiding. The idea, thought it never saw full execution, was to try and balance his overpoweredness by keeping the setting in such a way that he was only involved in planning and used as a last resort, and for the idea that "are we screwed enough to alert them to where the ship is?" being a constant thought on people's minds. Of course, the other thing on people's minds was that Core was full of bullshit anyway and has been and always will be a Machine plant, but those people were kind of dumbass in universe. Core may have been logical, emotionless, and a master of the quizzical tilt when it came to understanding concepts he had no knowledge of, but he'd made his decision quite openly and fully intended to stick with his course of action. Overpowered in universe, as previously stated the Matrix equivalent of a Terminator, he was a pretty fun character to design and write. But I always enjoy my logical robots. You did not just see Core standing in the closet.
Contrasting characters, the first of whom isn't mine are a) Guardian - a rebellious Sentinel-class machine who was much more emotive and human-seeming than Core ever was, and b) Brandiliea, his dragon-adoptable bond who was basically every young punk teenage girl trope we could think of rolled together into one bitchy and enthusiastic lesbian package.