"Katsuki, this is the new stepson of Earl Toshinori." Mitsuki introduced.
The boy was small, scrawny, and freckled. He didn't look noble at all. Had Toshinori REALLY married a common woman? With a bastard child no less?
"He's going to be staying with us for a few days." Mitsuki continued, "please be nice to him. You two will be working together a lot in the future."
Katsuki scoffed but didn't argue. He didn't want his mother to scold him.
"Why don't you two go play in the garden with Eijirou." The hag suggested.
"Fine. Whatever." Katsuki sighed.
As he walked away, the other boy followed. He was quiet, shy, and stuck close to the young prince.
When they reached the garden, it was to find a small, red dragon chasing butterflies in the grass.
"You have a dragon?" Izuku asked in awe.
"I don't HAVE a dragon. I'm friends with one." Katsuki crossed his arms, puffing out his chest in pride.
"That's so cool! Where did you meet him?"
At that point, Eijirou wandered over, shifting into his human form. He was still sort of new to this ability, so he took a while to do it.
"He found me in a cave." Eijirou explained. "My mom was dying and he tried to help her."
"Woah!"
The two really hit it off from there. They played in the garden all day, chasing butterflies and playing in the flowers, doing all the things Katsuki didn't really enjoy.
Seeing him so happy, Eijirou that was, made Katsuki feel strangely sick. He didn't know why since normally he liked seeing Eijirou smile.
When dinner came, the two were still chatting, learning so much about each other. Katsuki picked at his dinner, trying to swallow the sick feeling down along with his food.
He was jealous, but he hadn't realized it at the time. Eijirou had always been undeniably HIS. So when his attention was so focused on somebody else, it drove him mad with envy.
Of course, he didn't know it was envy at the time. He just thought Deku was an awful person. Because of course he was. Eijirou was too friendly for his own good. Katsuki needed to shield him from all the terrible people who wanted to get to him, to keep his dragon powers for themselves. Eijirou was HIS dragon, HIS friend. He couldn't let anybody use him for their deeds.
"Kat, you okay," Eijirou asked that night after the pair was tucked into Katsuki's bed. Izuku was sleeping in Eijirou's room, so it was only natural for Ei to come here.
"I'm fine." Katsuki grumbled.
He really wished he had opened up back then. If anybody understood Katsuki, it was Eijirou. They had been together since the beginning, after all. The two of them had shared toys and adventures and dinner countless times. If he had simply spoken to his friend instead of ignoring the problem, maybe Katsuki wouldn't hate Izuku so much. Eijirou could convince him to open up his heart.
Maybe if he had opened up back then, he would have felt a lot less alone.