The 'Starscream' from Energon and Cybertron is a Clone with a different Spark
Starscream in Armada transitioned from a reboot of G1 screamer to a Noble Demon who was still loyal to Megatron and the Decepticons, but had a sense of honor, integrity and cared about the Humans. In Energon he was Megatron's slave, but then, with his free will restored, in Cybertron he became an amoral manipulator who tried to kill humans for a distraction. How is this reconcilable from the guy we genuinely mourned when he died to unite the factions against Unicron? Simple, when Alpha Q recreated him he copied Starscream's body, perhaps even his memories, but it was a different spark, a less noble spark. This isn't Starscream, it's Starscream II Megatron was created by Unicron to begin the War
Megatron was once a Cybertronian who was consumed by Unicron. Millions of years later, in an effort to divide the Transformers to prevent them uniting against him, Unicron recreated Megatron as an engine of destruction to begin a war. This war would be amplified with the Mini-Cons, who would destroy them when the time was right.See here for the specifics: https://dragonkeeper19600.tumblr.com/post/56228582417/fan-wank-time-armada-megatrons-background
