Optimus Prime made his way through the desert canyons, admiring the diverse beauty of the planet when he heard crying, young crying. He searched for the source with his optics and tracked it back to a small child.
It was a little boy, dirty and in ripped clothes too big for him. He looked up as the Prime approached but couldn't summon the strength to try to run. He was exhausted, over heated, hungry, and thirsty.
"You are far from the nearest settlement, child. Why have you come here?" Optimus knelt.
"Father left me here."
"Abandonment is not typical of your species. Is he returning?"
"No. He doesn't want me."
"Then you should be taken inside before you offline." Optimus laid his servo beside the child.
The boy crawled weakly into his servo with a backpack and nothing else with him. Optimus put him inside his cab and cranked the AC. He drove as fast as he could to the Ark, hoping one of their human friends was still about. When he arrived, he stepped inside, taking Cas out.
Spike was there.
"Back already, Optimus?"
The sight of the adult relieved Optimus. A human could really help the little one. He knelt and showed the boy to Spike.
"What have you found, Optimus?" Spike took a closer look, "He's been in the desert too long."
"He says his Sire abandoned him out there. He needs help, Spike."
"He needs water and to cool down. Bring him inside the Ark."
Optimus hurried in, and Spike ran to get water and shouted at the nearby twins to get Ratchet, who had been learning how to take care of humans as well as Transformers.
Ratchet was in his medbay and looked up when the boy was brought in. He was gulping down a big water bottle now from Spike, and Optimus looked anxious as he watched the little one.
"He's tired and over-heated," Ratchet determined, "Plenty of fluids and rest should help."
The boy looked up, taking a breath between drinks.
"Um... can I... have something to eat, please?"
"Sure. We keep a fridge here."
Optimus took him to the rec room and opened the fridge. "What would you like, little one?"
"Just cheese? Don't you want anything else?"
"How about a ham and cheese sandwich and an apple?"
Optimus pulled out the pre-made sandwiches Spike liked to bring and a Honeycrisp apple for the boy. The twins came over as he sat on Optimus' knee.
"Hey, kid, what's your name?"
"And I'm Sideswipe."
"Hi," he said around his sandwich, which he was eating like he was starving.
"Do you like video games?"
"I don't know. I never had any. I just built stuff."
"Like what?" Sideswipe asked.
Cas pulled a little robot out of his backpack and showed the three mechs.
"Cool! Does it work?"
"Yep." He set it down and pulled out a remote, moving the robot around and having it clean up his plate.
"That's amazing. Did you make it up or was it a kit?"
"I made it up with stuff I found around the junkyard Father ran."
"That's quite a feat," Ratchet was impressed.
He shrugged, "I've always been good at it."
"Did you ever build anything else?"
"Yeah... but Father smashed them all. I hide this one since it was so small."
"I'd love to help you build things!" Wheeljack smiled.
Cas smiled shyly.
"Come down to my lab sometime."
Soon it was just Ratchet and Optimus left with Cas. Optimus was stroking Cas's head idly. The boy was nearly asleep.
"Well, Optimus, what do you plan to do with him?" Ratchet asked.
"He can stay here as far as I'm concerned."
"He needs at least one parent, Optimus. The whole base can't parent him. It wouldn't be consistent."
"I'll be his father then."
"Really?" Cas asked softly.
He looked at the Prime.
"You... really want me?"
"Yes, little one. Of course."
The little one smiled and hugged his digit. Optimus crinkled his optics in his own smile.
"Well you better get him settled in your quarters then."
"Come with me," Optimus picked up Cas gently.
They encountered Prowl and Jazz in the hall.
"Who's the bitlet, Prime?"
"Prowl, Jazz, this is Cas, my new son."
"Hi." "I'm Jazz, this is Prowl."
Prowl was staring at the child and Prime.
"Something wrong, Prowl?"
"...Optimus, you can't keep a human. They require their own species for healthy development."
"It was his own father who abandoned him in the desert to die, Prowl."
"..." Prowl crashed.
"Is he okay?" Cas asked.
"...He's been shocked, that's all."
"He'll be fine with our human friends around, Prowler, and we can homeschool him, can't we?"
"I suppose so," Prowl recovered.
"He's already skilled at robotics," Optimus praised.
"I'd like to see what he can do with some real tools."
"I'm sure we will in time," Optimus said.
"Of course," Jazz smiled, "Bitlet looks tired."
Cas yawned and rubbed his eyes.
"I'm taking him to get into berth," Optimus replied.
"Go on. Get him to berth."
By the time Optimus reached his quarters Cas was asleep. He tucked Cas down in a small, padded box.