Before the Cybertronions came to Earth. The humans had been working on a project called Umbra Ex Machina. Also know as Spirit Machine. They want to create a sentient bio-mechanic robots to ward off off world invaders. At first it started out innocent they nearly wanted to protect their world. But as time went on and subjects after subjects continued to die there morals twisted and started to use humans to implant sentience into the robots. This left nearly every human they had dead. Finally the governments stepped in and disabled and annihilated the program. The few scientists left for the project went underground. They developed the idea of created bio-mechanic organism that was incredibly hard to kill and had the systems of a human and machine.
They kidnapped more subjects mostly homeless people or runaways but then they realized most of the subjects were never healthy or youthful enough to survive. Until they took a pair of twins. The twins themselves were well loved and known in the area they lived in and both fairly young and full of life. They were only children when they were taken, the kidnappers believing that they were running away from there home as they stayed out late in the area far longer than they should have been. They were experimented on until the age of fourteen, being the only ones to survive pass the initial phases. They escaped after a guard was leading them through the forest terrain for their daily exercise. They ran and ran until they reached a random city in Arizona. They tried to hijack a yellow beetle car but it ended up being a sentient Cybertronion named Bumblebee. After a round of screaming in fear the girls started to talk to Bumblebee and after their conversation he contacted the authorities to take the girls home. The girls relieved thanked Bumblebee and conversed with him about how he arrived on Earth( though the girls were still wary of him because he was bigger and stronger then them).
The police arrive and the girls thanked him and we’re going to leave with the officers until they recognized one of the policemen as the guards from the labs. In absolute terror the girls ran and thus the chase began. Bumblebee confused chased after them, surprised they can run as fast as they could, past any speed of any human he knew. After a while of searching the police sent out a bulliten on the girls that if spotted to call the station. Bumblebee found them near the ark after five days of going to find them on his breaks. The girls apologized to him and told him that one of the policemen was one of the guards from the lab. They rather die than be captured again and told him that they intend to go home on foot. Refusing to let that happen Bumblebee contacted Spike and Carly and asked as a favor to let the girls stay with them until it can be arranged to let them go home.
After a while it was initially well the girls helped Carly around the house and with Daniel and they finally had a plane ticket to go home. Thanking them they promised to call when they got there. A month later with no call or letter they started to get worried, and then Bumblebee disappears. Jazz as head of special ops goes searching for him with Mirage and Hound. But then are stopped by the deceptions, fighting with them the learn that apparently many of their weaker members have disappeared with no trace. With the probability that these are connected contacted their leaders, and thus the hunt for their members begin.
After much theorizing they realize that the decepticons that were taken were not just infact weaker but younger. And that Bumblebee was the only autobot taken. They get a call from on of the girl twins warning them about Bumblebee. She tells them that she and her sister were experiments of a an underground project and that the project had been take to what she realized two weeks after she came home were infact Cybertronions all wearing purple insignias. They men from the labs had found her and her sister in ther home town. They killed everyone in the town to ensure no witnesses and burned the houses. She had been on the run looking for help because her sister sacrificed herself to ensure that she would get to the autobots and gain there help.
In the last picture Bumblebee is in the lab. He finds himself paralyzed and that he can only move his head, he sees one of the twin girl unconscious in a container filed with fluid and connected to many wires. As he tries to regain motion in his body he sees a large humanoid robot that can easily be in size of Omega supreme. It was red and sleek and looked almost organic.