Starscream

Information
Starscream is the 2nd in command to the decepticon cause, but constantly tries to overthrow Megatron any chance that he can get.

History
Starscream was not always a Decepticon under Megatron's command, nor was he ever an Autobot serving Optimus Prime.

For over a thousand years, Starscream was in command of a space station orbiting Cybertron. Alongside Jetfire and his fellow Seekers, Thundercracker, and Skywarp. He was tasked with collecting and researching great quantities of Energon. Some time before receiving this post, Starscream was a powerful Sky Commander, but apparently had some sort of fall from grace that reduced him to this menial task. This station also housed the last known samples of Dark Energon, a dangerous power source known to be uncontrollable and deadly, with the ability to corrupt and destroy anything it comes in contact with. This made it a prime target for Megatron in an attempt to deal a final blow to the Autobot forces. When a small Decepticon task force, lead by Megatron himself, invaded the space station, Starscream warned them that his quest to gain Dark Energon was foolish and would only lead to his own destruction.

Despite the station's defense systems, Megatron was eventually able to break through and find the hidden sample of Dark Energon. In a last ditch effort, Starscream attempted to destroy the sample himself, but to no avail. Despite his warnings, Megatron made direct contact with the Dark Energon, and revealed the unprecedented ability to actually control the substance. Starscream was not only stunned, but impressed, and after seeing him use the Dark Energon to destroy the soldiers under his command, offered to join forces with the Decepticons, by giving Megatron the station and telling him he knew how to manufacture more Dark Energon, on the condition that Megatron would teach him to control the dangerous power himself. Jetfire, of course, was not too happy about this.

Later in the war, Starscream set a trap and succeeded in capturing Optimus Prime and bought him before Megatron, in return, he got shot in the face for bragging his mouth off. But after Metroplex had woke up again and destroyed Megatron, Starscream announced himself the Leader of the Decepticons, however, it was short lived because once Soundwave finished fixing Megatron up in his laboratory, Megatron returned to seize his throne, and exiled Starscream from the Decepticons.