Optimus Prime:
He always appreciates it when you take time to listen. But to be honest, his stories of his life back on Cybertron are always intriguing. Nostalgia. So when you beg for more, or usher him to go on. He can't help but comply with your requests. These moments bring you closer together and help you understand one another better.
Bumblebee:
Playing video games or watching TV is usually something Bee tends to do with the humans, but who says you can't get in on the action as well? Since you both don't have a full understanding of whats going on on the television screen, its absolutely adorable to try and figure it out together. *tear* Stay young, kids.
Ratchet:
Now most people might think, a sweet moment with the Autobot medic? Preposterous! However, Ratchet isn't always grumpy. He just gets easily irritated when people break his things. And who wouldn't? So the best way you guys have "that" moment is when he realizes something is broken, "Y/N, I NE-" Cue you holding up whatever he was about to complain about, with the remark, "Needed that?" His way of saying thanks, makes it all worthwhile.
Smokescreen:
Every moment with this firecracker is adorable. His personality is similar to Bumblebee's, but he can talk. That being said, looking up at the Earth sky at midnight calms his energetic mind, because he realizes that the dark sky can be full of twinkling stars. But their brightness dulls in comparison to you. Hearing such a passionate compliment from Smokescreen, makes the moment all the sweeter.
Megatron:
Much like Optimus, Megatron enjoys telling his own tales of Cybertron. You weren't there to witness the past gladiator of Kaon. Or the rebellion against the High Council. As the Deceptions became their own faction, Megatron knew he could never be Orion's friend ever again. "We were brothers..." He glances at you, looking up at him, fully attentive with genuine interest and curiosity. He sighs, "Once." Your methods of trying to cheer him up are always enlightening.
Soundwave:
Oh sure he's a smart mech. Any one could infer that, so thats why correcting him while he's working on coordinates or codes of some sort make him a bit embarrassed. And for a 'Con that barely shows emotion, its pretty cute. First he's just taken aback, stares for a long moment, and a smiling emoji appears on his dark visor. Gotta do that whenever you can.
Knockout:
We all know he takes great pride in his appearance, but to be actually complimented on it? His faceplates can become as red as that well-polished finished. No matter how hard he tries to coolly play it off. "You look really nice today, Knockout" "Why, thank you sweetspark" "Really really nice, I mean it." "Er- thanks.." "You're absolutely welcome, hottie!" *glitch*