Rodimus puts a hand to his mouth, his expression unabashedly distraught. This almost seems like an opportunity to explain himself, but Rodimus knows better than that now...he'd made some serious mistakes in the past couple of weeks. Some mistakes that even he knows there's no explaining in the world that is going to make right.

"I...okay. Okay." He vents a sigh, steeling himself as he scrambles to organize his thoughts. "It's not...it's not really all that complex, I suppose. I um...I thought, when you were still Orion and, and things weren't looking all that great that I would..." He hesitates briefly, feeling suddenly very self-conscious. "I decided to....um.....infiltrate the Decepticons. You know, to gather intel. I thought I could do more good doing that than sitting around the base doing...nothing."

He pauses, clasping his hands together, looking down, unable to bring himself to look at Optimus while he explains.

"And I...." he exhales a vent sharply. "I didn't tell Arcee."

He fully expects a bad reaction at that, so he doesn't leave a window for one, and instead plows ahead, speaking rapidly as he does.

"I spent some time tracking them down, and when I did, they let me join up with a little convincing and...I...traded them some non-essential intel. It - it wasn't anything that would hurt anyone, just bits and pieces. Miscellany, really. I was there for almost two weeks and I didn't find out anything. I didn't even know you were there, I swear. It was...it was a waste of time.

"And besides," Rodimus' expression hardens briefly. "Obviously, it turns out they'd been on to me the whole time. I know, it was stupid. I was stupid. And. Well. Here we are."

It's a rough version, and it's watered down, but that's pretty much it. Minus one small thing...the thing that he's most concerned about sharing, and he hovers precariously on doing so, deciding to give Optimus a moment to react first.