The answer to an ages old question.
Megatron caved in to Unicron’s demands in Transformers the Movie because Unicron enlightened him on what awaited him in hell if he failed to cooperate…
Megatron: “I belong to nobody!!!”
Unicron: “Perhaps I have misjudged you. Proceed on your way to oblivion; where you will spend eternity with no one except countless poorly conceived Mary Sues who will bewitch you with their unrivaled beauty. You will be overcome by warm fuzzies, nagged mercilessly to forgive and make nice nice with those who have trespassed against you, and worst of all, you will be twitterpated. Twitterpated, I tell you. You, once a proud warrior and leader of an army and empire, will be reduced to an eternity as a lovesick husband and father; a mere shell of your former glory. But if that’s what you *really* want…"
Megatron: “Noooooooooo! No! I accept your terms. I ACCEPT! AHHHHHHHHHHHHHHHHHHHH!!!"
Unicron: “Excellent!"
This next bit was inspired by friend's comment after I posted our sparking theory collaboration on DeviantArt.
Starscream: O_O "TOUCHING MAKES SPARKLINGS?!"
*Megatron and Soundwave look at each other in utter stupefaction before bursting into laughter.*
Starscream: "I fail to see what's so funny!"
Megatron: "Don't tell me you failed sex ed, Starscream?"
Starscream: "What?!!! Me, Starscream? Fail sex ed? Never!"
Megatron: "Then how could you not know that feeling up a female Transformer and transmitting spark energy produces children? Sparklings are sexually transmitted diseases you dolt!"
Shockwave: "If I may, Mighty Megatron...?"
Megatron: "Not now, Shockwave. Not now!"
Shockwave: *pushes his luck* "But Mighty Megatron, Starscream's ignorance would explain the exponential increase in seeker population over the years. In fact, the only time seeker numbers plateaued was during the four million years that you were all in stasis lock on Earth."
"Megatron: ... You have to be shitting me, Shockwave."
"Power flows to the one who knows how; desire alone is not enough." - Megatron
The Scrap Heap
One by Metallica(Megatron remix)
Mighty Megatron Angry Mix by Tony Bacala