One day, exploring the forest, he found a small rattata.
He cautiously approached him and had his pokeball ready to catch it, but the little rodent noticed his presence and quickly leapt towards him, biting his arm, only to then flee into the deep forest.

The guy then fell to his knees in pain. His arm had swelled up, and he quickly felt dizzy. Before he could have opened his backpack and obtained a healing potion, his arm began to mutate, and a thick amount of purple fur began to spread from his limb, moving up his torso.
He panicked, just as he felt his body shrink, and his head, arms, and legs transform into what appeared to be those of a rodent.
In less than two minutes, the transformation was complete. He had shrunk completely, and now had the appearance of a rattata.

He looked dazed and scared at the same time at his new body, looking at his furry legs and arms. His clothes, now huge for his small size, lay on the floor, next to him.
He wondered in distress what he should do next, and quickly decided to run in the direction of the nearest town, which was only a few minutes away.
However, after a few meters of travel, he noticed that the journey was now much longer for a small rattata like he was now.

Then suddenly, he heard footsteps behind him. He turned and saw a young man watching him from behind some bushes.
Desperate, he tried to ask her for help, but only a scream came from his mouth. A rattata screech.
After a few seconds of confusion, and already resigned to not being able to communicate, he ran towards that young man making desperate signals with both arms, praying that he could be understood.

-What is it, little one?- He had never seen a rattata so friendly as to approach a person that way... -do you want to be my pokemon as much as I want you to be mine?

The rattata stopped short. A cold sweat ran down his back as he observed that the young man in front of him had a pokeball in his hand.
Backing away in anguish, he continued waving his arms as he yelled to stop, that he was a human, but again, a sharp rattata screech emerged from his mouth, as the young man threw the pokeball at him, from which a crimson lightning bolt emerged, turning everything around him into darkness as the pokeball engulfed him.

He did not know how long it was since that.
Upon being freed from that pokeball, the first thing he observed was that young man again, looking back at him.
He smiled and proceeded to pat his head. That felt good.

-What a pretty rattata you are! Good boy! We are going to be good friends! - said the young man without ceasing to caress him.

It was true. He was a rattata.
He emitted an affectionate squeak towards the young man, playfully.
After all, his name, his past life and all his memories of when he was a human had all faded away from his head.
His mind was now that of a Rattata. He was a rattata.
A carefree rattata ready to cheerfully obey his master's orders.