"My Autobots and I thank you for allowing us to rest outside your home," Optimus rumbles. He's in his alt mode, with you sitting in the front seat. The seatbelt is off and his voice feels like its coming from every direction.
Really, it was the least you could do. The Autobots don't often have a safe place to rest, and you enjoy their company.
"We have had... A long day," his voice is soft, most likely to not wake up the other Autobots that have already fallen into recharge. But, Optimus seems to notice the look on your face. "And it seems as though you too, have had a long day. Or, at the very least, had a day that seemed very long."
He's right, and it seems as though he knows it. "If you wish, I can tell you a story to help you relax? You seem tired, and stories tend to help Sparklings fall asleep."
When you nod, you can feel Optimus' joy through the subtle shift of his weight. "I have a blanket under my passenger seat, if you wish to use that.*
Sure enough, when you look, there's a big, soft blanket folded neatly under the passenger side seat. It's blue and red, the same colours as Optimus.
Slowly, Optimus turns his interior lights off and adjusts the drivers seat that you're in so that you're leaning backwards comfortably.
"My apologies, that's about as far back as my seats will go." Optimus explains in a softer voice, the only light inside of him being his steering wheel that glows a faint blue every time he speaks.
"I have not told this story to anyone before, so I am unsure if it will bore you, however, I think you'll enjoy it. Feel free to close your optics and relax, I will not allow any harm to befall you. You are aware of us Autobots of course, but I don't believe that you've heard too much about our enemies, the Decepticons."
"Another thing you may not be aware of, is that I wasn't always called Optimus Prime. Once, a long time ago, I was called Orion Pax, and I was best friends with a bot named D-16. The bot who would go on to become Megatron. The leader of the Decepticons."