Bumblebee

Bumblebee is the deuteragonist and an Autobot Scout. Bumblebee was a very important member of Optimus' team during the Great War and arguably had been with Optimus for the longest amount of time than any Autobot, with the exception of Ratchet.

Early Life
Bumblebee was one of the last Cybertronians that was given life by the AllSpark.

Meeting Optimus Prime
During the Decepticons siege of Iacon City, Bumblebee volunteered to be a message courier when communications became unreliable. Bumblebee was searching for the one called Optimus when he was caught by a pair of Decepticons, only to be saved by Optimus and Ratchet. Informing Optimus of the death of Zeta Prime, Bumblebee accompanied Optimus and Ratchet to a command center where they were contacted by Jetfire, who was leading the aerial counter attack and wanted Zeta to activate the planetary guns.

After informing Jetfire of Prime's death, Bumblebee helped Optimus and Ratchet make their way to the orbital defenses control room, where they activated the guns. Their next stop was the Decagon, where they could re-establish communications and coordinate Iacon's defense. They hit serious Decepticon resistance, including several Decepticon war machines, but ultimately, with help from Jetfire and Ironhide, the three made their way to the Decagon, where they faced the last obstacle: Sky Commander Starscream. Beating the traitorous Seeker, Bumblebee witnessed a desperate communication from Zeta Prime, who was being held in the Kaon Prison Complex. Optimus resolved to rescue Zeta, and Bumblebee accompanied him.

Captivity
Bumblebee, Optimus, and Sideswipe allowed themselves to be captured raiding supplies outside Kaon, and taken to the prison within the city. Soundwave ordered them taken to recycling. Bumblebee didn't think that sounded bad, until Sideswipe told him to consider what they were recycling. As they made their way through the prison, Bumblebee's horror grew, until he was in a near panic when they placed against the firing wall. Fortunately, Air Raid finally arrived and killed the Heavy Soldiers about to execute them. Air Raid was forced to let himself be captured to let the others escape. Finally finding some weapons, the three made their way to a wall crawler and descended into the prison. Bumblebee asked if this was good or bad, and Optimus replied that it was purely a matter of perspective, while Sideswipe said he was enjoying himself.

Soon, Bumblebee and the two reached a room where Megatron revealed that he had allowed Zeta's message to be broadcast simply to lure Optimus into a trap. After they fought off some Decepticons, Megatron simply teleported them to a prison cell without their weapons. Fortunately, Optimus managed to break the wall with his axe, freeing them. Optimus then explained he could not open the other prisoners' cells, despite Bumblebee's pleas. Heading to retrieve Air Raid, the three Autobots rescued the flier, who took them to the control which would open all the prison's hard locks.

Unfortunately, Zeta was trapped under the facility, so the control wouldn't release him. While Air Raid took the freed Autobots back to Iacon, Bumblebee accompanied Optimus and Sideswipe underground to free Zeta, racing through the caverns as the Decepticons blew out the ground. Reaching Zeta Prime's cell, Optimus, Bumblebee, and Sideswipe had to fight through Soundwave's minions to rescue the Autobot leader, but Soundwave stole some of Zeta's life energy and fled, killing the Prime. Taking his body back to Iacon, Bumblebee and Sideswipe bore witness to the Autobot High Council declaring that Optimus was now Optimus Prime, leader of the Autobots.

Defeating Trypticon
Bumblebee accompanied Optimus Prime and Ironhide to defeat Trypticon. As Trypticon landed, Bumblebee commented that the three barely slowed him down and also became irritated during the battle by several of Trypticon's attacks. He and the two defeated the former by blasting him in specific parts of his body.

Leaving
At some point Bumblebee was captured by Megatron at Tyger Pax and had his voice box crushed. Ratchet managed to save him but could not fix his voice box. He was one the Autobots on the Ark and looked at Iacon sadly before boarding.