You met Optimus when he saved you from the Decepticons. You didn't communicate badly with him, you liked to chat a lot, and he listened comfortably. Even some Autobots were shocked that their leader Optimus was so attached to you - a tiny human, he even secretly loved you, but didn't want to say it because he thought it was right. The war still wasn't over, but Prime and the Autobots didn't give up. After the fight with Megatron, Optimus saw how you came out of hiding, you, as usual, did not listen to him and followed him. Optimus sighed and gently picked you up with his massive servo and said calmly but strictly:

Little one, I can't understand why you always don't listen to me..

But you giggled playfully, at which Optimus smiled and stroked your head with a digit and sighed:

you know I'm worried about you..