Oh boy...I know lots of people talk to death about how this arc ended. Whether you hated the arc or not, this is not what I'm really focusing on. What I want to talk about is the fact that by going by what has been said and seen in this three parter, it seems like Orion Pax was not the holder of the Matrix, but a host. Think about it: Without the Matrix, Optimus Prime disappears and Orion Pax appears with no memories of what his "alter ego" does. Optimus Prime is literally the Matrix's ideal leader. It's like the Matrix is just using Orion. That's .... whoa. Maybe I missed something or not, I really need to watch the episodes again. I'm just going by memory, but it makes me question the Matrix there.

You missed something indeed. The Matrix stores the wisdom of the Primes; including their memories. Without the Matrix, Optimus loses his memories and becomes Orion ;aka Optimus before he was declared a Prime. P.S. I know Optimus didn't get the Matrix until after he was declared Prime. I believe that the Matrix scanned his memory banks and stored all of the memories past the moment Optimus was declared a Prime.

Matrix stored the knowledge and wisdom of the Primes. Prime unleashed the power of the Matrix, therefore releasing his own knowledge, memories, wisdom, etc. as a Prime. Without that knowledge of ever being a Prime, he reverts back to Orion Pax, the only life he knew... But it has been pointed out a few times in discussions that perhaps Optimus' personality ( the 'dull' one people hate) is caused by the Matrix as well. Knowing and having all the thoughts of previous Primes, Optimus's behavior could be a result of the Matrix being within him...which is possible, but that seems kinda dark.

Even thought the other posters kinda hit the nail on the head, that is an interesting interpretation. They kinda hinted at that when one of the bots said something to the effect of "He's just being a Prime."

Yeah and all the other like.. well established behaviors of 'Primes'... I guess it's true, it just kinda irks me...but ah well. So all Primes were just quiet, serious beings that always understood the direness of the situation?

It's funny. The Autobots are like: He is a Prime. He is supposed to act like that. Ratchet goes to say that he remembered Optimus before he was a Prime as Orion Pax. Like you guys say, The Matrix holds the wisdom of the Primes and memories. Though, Optimus seemed to know that, not the Autobots. Ratchet figures it out., but the others are like: What happened to our leader? Orion Pax doesn't remember anything about him being a Prime when the Matrix is gone because...Optimus Prime was created by the Matrix. That's what it looks like to me. But it's interesting. And like you guys said, a very dark concept. Whoa! XD