1 3rd Times The Charm

The doctor and his companions had once again managed to fight off the invasion force of cybermen sent to convert the Earth. The cybermind was bested and all of the cyber fleet's ships were set to self destruct. In a last ditch effort to conquer this timeline's earth, the cyber planner released a vast swarm of cybermites down into the atmosphere. Where ever those machinations were to land they would convert all matter of organic beings into cybernetically enhanced organisms. The doctor had set his Tardis to transmit an even stronger frequency which fried every last mite, cept for one. The cyber planner had learned from it's mistakes and planned for failure this time around. It had sanctioned the creation of 1 2nd generation cybermite, It's role is to act as a miniature cybermind and eventually turn an organism into a cyber planner to help with planetary conversion. this one was tuned to a different frequency than the rest which the doctor had no time to crack. As the ships began to blow up one by one the Tardis began to dematerialize and enter the time vortex.

Along came a spider.....

The second generation cybermite was holding onto the Tardis as it span through pure primordial chaos, eventually the Tardis was struck by a temporal discharge ( lightning bolt) which caused the mite to lose its grip and fall outside of the time line. By sheer coincidence the place where the mite fell was actually a weak point in the universe... a rip in the fabric of spacetime. It quickly passed from this dimension to the next and suffered un-notable damage. The mite began to fall at a rapid speed from quite the height. It spun and tried to stay belly down as it fell, its too small and doesn't have much weight so it can't reach terminal velocity. Even if it hit a solid steal floor it would be fine. Eventually buildings came into view,

This is great! thought the mite.

A city is a wonderful place to start an invasion. First cybermites take over as many organic beings as possible to gain vast amounts of economic and social power. Then slowly begin to fill the general populous with more and more cybermites. Then.... BAM! activate the mites and instantly convert everyone. Had more mites survived then this would have happened in cities the world over. But one city of cybermen should be enough.... It's always enough.... when The Doctor doesn't meddle.

This was the third reality ( technically ) that the cyberian race has gone to, hopefully this time, The Doctor doesn't exist. Hopefully, that old human expression rings true....

Third times the charm.