OK so this au has been bouncing around in my head for a little bit now so I figured I'd throw to Tumblr
So post-predacons rising, Knockout works as a medic for the autobots and is the main medic, since ratchet is on earth. Eventually bots, cons and neutrals begin returning. Medics like first aid and velocity then take control of medical facilities. Eventually people don't want a medic without a medical degree. Because of this knockout kinda gets kicked out.
Flash over to shockwave who has been hiding out in one of his underground laboratories. He has been helping predaking, skylinx, and darksteel recreate their species. The lab has a large ceiling and resembles a dome of sorts, but it has little ledges that they perch on.
Somehow, predaking finds knockout and brings him back to shock's lab. Shockwave agrees to give shelter to knockout in return for another approach to restoration of a species. They work on the project and eventually, Knockout starts his own side project. He starts trying to recreate cybertron's flora. Eventually, he recreates a few species of "plants". A type of copper wire vine, energon flowers, a weeping bolt tree, and other things. Soon flowers are all over the lab. Shockwave decided to expand the lab and discovered a natural energonfall. The first one discovered in over 4 million years.
The two scientists decided to not stop at just predacons and a few plants. They recovered fossilized remains of many life forms. Avian species of Vos, the burrowing species of kaon, the marine life of the praxian energon pools, and many many others. They kept many of the flora and fauna in the lab to monitor their behavior. Eventually they released some of the creatures onto the surface.
Sometime after, the autobots discovered the source of the sudden animal re-population of cybertron. They offered shockwave and knockout an official job and started building an above ground lab connected to the original.
So now they have this huge lab where there's animals living in both labs. Eventually bumblebee suggests that anyone struggling to readjust to post-war life, anyone struggling to make a living, and anyone who needs a fresh start, can live at or near the labs and help out with all the chores at the lab. Misfire, fulcrum, blitzwing, whirl, Soundwave, and even starscream will help out. (Even though screamer only stops by occasionally. Soundwave always helps with the feline and Avian species.) They get housing and food, and they don't have to interact with the people they hate. (Knockout keeps track of rivalries to separate them in the schedule). Eventually they start to rehabilitate the planet's diversity and some of the people as well.
And if at one point shockwave saw knockout getting excited about new flower species, and wanted to feel some of that excitement about all of this. And if they worked on a way to slowly reverse the shadowplay, no one has to know.
People do know. They notice it slowly. Shockwave is still a bit cold towards people, but his kindness for the creatures he brought back from extinction is very obvious. Someone who knew him before the war actually started to recognize him again. When he made a small pun knockout couldn't stop smiling. Knockout himself found something that he can finally get behind and adore. He finds himself caring more about the turbofoxes and drones of paradise than his finish. (When he realized this, he had a mental break down.)
Overtime, they helped spread life into cybertron. Although the alspark was starting to create life again, these scientists helped excellerate the process. Beautiful rivers of energon are now filled with aquatic species with banks of delicate flowers, and skies are filled with seekers and bird drones.
When Megatron comes back to cybertron to deposit the djd in prisons, he stood over cybertron and saw that the world he destroyed was healing. He smiled before continuing his journey to right even the smallest bit of the crimes and atrocities he committed.