Well, I watched the Season 3 episode "Grimlock's new brain" today for the first time since I was maybe 8 or 9. Everyone knows, that remembers the episode , he created them from scrap metal that was lying around in Unicron's head, assumingly from the internal death traps/anibodies he used while he was alive. What I really want to know is how did Grimlock instill a life force into them? It was never shown. Did he siphon from Unicron's spark/energy? If so, shouldn't they be worried that one day they might turn agains the Autobots to help revive the chaos bringer, bound by sharing part of the same spark?