As much as he tried to hide it, you can tell something’s wrong.

Optimus was never the loudest, sure, but now, he's quiet as a mouse. His resting face now is a slight frown… he nearly always has his head buried in some kind of assignment.

You didn't get to acknowledge it before you were sent off to a mission, but you could see what was wrong by the look in his eyes…

He misses Elita-1.

She had her spark extinguished just recently, before Team Prime landed on Earth, you aren't sure of the details, but knowing Optimus, there's no way he doesn't blame himself.

You come back injured, it isn't anything life-threatening, but, that doesn't stop Optimus from fussing over you. You'd be lucky to get an emotional word out of him at this state.