system
Given the following post, respond as if you're commenting on Reddit:
human
[Transformers] Why did Megatron ever tolerate Starscream's constant shenanigans?
gpt
Starscream was Megatron's acknowledged heir. He was also, self-evidently, the worst possible leader for the Decepticons.

That means that anyone who wanted to launch an effective coup against Megatron would have to either kill or suborn Starscream first. And Starscream has two useful qualities: cockroach-like survival skills, and an arrogance so massive that he would never consent to be someone else's puppet.

This adds up to Starscream being a useful buffer, and a coal mine canary. The Decepticons are, by nature, treacherous and power-hungry, but Megatron knows that he'll be able to see any attempt on his life coming by simply watching Starscream.

And he also knows that Starscream, for all his cunning, ruthlessness, and durability, is far too incompetent to actually overthrow Megatron.