Professor Duncan Gills checked his watch. Forty-five minutes. That's how long it had taken him to change the face of robotics… the Foundation, and maybe even the world. He gazed down upon his creation, the result of so much soldering, grim grubbiness, machinated cogs, and even a little bit of luck. It was a short brass automaton, with lightbulb eyes and a smile that could light up an entire Christmas tree. Reverse engineering two skips into one, glorious unit. They'd fund his research now!
Mister Brass, or what used to be him, was laying peacefully below, covered in beautiful grooves and gears and all sorts of fanciful mechanical claptraps. This was his Coup de grâce, his finest hour. With this, the clockwork virus no longer had to be feared. Far from it! It would become the source of new Foundation drones, who would march out of his laboratory and across the earth, until the entire world was in their loving grip.
Breathlessly, he leaned down to his new creation. "Brass, can you hear me? Are you there? Please, say something!"
He was answered with an iron grip on his throat, and a mechanical, monotone voice booming in both of his eardrums, like the little drummer boy had a twin.
"DESTROY ALL HUMANS."
Oh balls…

Dr. Gears looked up as the clanking sound that had just been outside of his office relocated itself to within.
"Greetings, Doctor Gills. I trust your costume is a result of the research is going well?"
There was no response, only the low hum of an internal twisting network of cogs.
"Is that a costume?"
The two robots looked at each other, then back to Gears. "NEGATIVE."
"I see."
As they reached for his face, Gears had one last fleeting thought. It was a silly one, from a man not usually prone to flights of fancy.
I suppose I really will be a Cog, now…

The situation quickly spread beyond the confines of the Site. Dr. Gills, instead of pacifying the clockwork virus, had instead mutated it to a new, more terrible and virulent form. Now, all would become Mister Brass, marching step with their confederates.
Step by step, they trode over the Foundation's most secure facility, bringing down every anomaly they came across. 682 became a set of three nervous, brass-bellowing bots with the twist of a valve and the cooperation of the credited collective. The senior staff tried their best to stop it. But it was all for naught.
Bright fell, when his chimpanzee body was unable to outrun their metallic grasp. His cold, monkey fingers went from being wrapped around a shiny metal throat, to being wrapped in glimmering bronze.
Clef was taken when he realized that not even a pact with himself would be enough.
When they came for Mann, he was fascinated, and wanted to study them. They might've accepted his offer, too, if he hadn't mentioned the de-bolting procedure.
Finally, one after another, the staff fell where they lay. Until one of few survivors stepped forward. A man who would be the champion to all. Dr. Kondraki, and his booterfly army.
He threw his might against them, breathlessly ordering his butterflies to swing through their ranks, bringing illusory powers in their wake. Alas, it was for naught. Their cold, unfeeling robo-eyes did not fall prey to the magic eye folly of man, and they took him like all the rest.
All seemed lost…

In one lone room, away from the frenzy, Researcher Zyn picks up one of the injured butterflies. Carefully cradling its wing, she whispers to it "…No, you don't deserve this fate."
Her next destination was Mann's lab… and with destiny.

The union of Brass was preparing for an invasion of the world. If the Foundation could not stop them with its greatest champions, who really stood any chance at all?
That was when they heard it. A fluttering, soft at first, but growing in power until soon, every one of their little iron eardrums was thumping in time.
They burst on the scene like the revenge of the sith, ravaging first the front ranks, and descending on the else. Butterflies with razor edges, ripping through the brass like it was tissue paper with brittle bones disease. As the men trapped in coffins of brass were liberated, they cheered. Soon, every man was free, and only the original infected remained. As it was cut to ribbons, it heard one last cry from its destructor:
"Reverse-engineer that, bitches!"