Shockwave is a logical being. Therefore, having a human pet is the only rational choice. Screw Starscream, yes, this is logical and totally not him being lonely

“Are your nutrition levels satisfactory?”

He asks the human. He’s not skimping out on getting his pet the most quality food he can smuggle. Yes his means of getting this human were…unorthodox, but he’s dedicating himself to this human’s care. They’re not just a lab rat or experiment. This human is…his.

“I shall be forced to inspect you should you not answer. Are your nutrients sufficient?”