Rotom
I float around the head of the little girl, telling jokes, her giggling. She looked up innocently and said:
"You're my best friend! You're funny, you don't make fun of me, and you can mess with the radio and TV! That's amazing!"
My already wide grin grows bigger. It was nice to have such a friend as her. I was lonely before in this big mansion, and now people are always going in and out of here. The girl and I constantly played tricks on the visitors, most which came from my mastermind. We would scare them by turning any of the electronics on and off, or making weird sounds and having things "mysteriously" move. I told her that it was my pleasure to play with her. She smiled.
"Daddy's going to have a lady guest tonight. Shall we plan something devious?"
"Like what? Making plates moving? Flickering the lights?" I inquired.
"No, something big! Like…making all the power go out! All night." She jumped a little with excitement for her thought.
"His lady friend will never come back!" I chided.
And so we started to work on our plan. We found out when the lady friend was coming, and when, exactly, we should turn of the power. I waited at the power box, while the little girl eavesdropped outside the dining room, ready to run down to the basement and tell me to turn it off.
All of the sudden, she fled into the basement, turned off all the power, and ordered me to enter the power box to make certain they wouldn't be able to turn it back on. I squeezed in, but the second I did I felt something was wrong. The surge of energy was too strong, and I heard her scream "Gastly!" Quickly, I pulled myself out of the box, only to find the girl charred, obviously dead.
Moving towards her, I realized that I wasn't a Gastly anymore. I wasn't even a ghost pokemon. Looking down at myself, I was some sort of absurd electric thing, barely floating above the ground. I gave the girl a moment of silence before incinerating her body completely, removing any evidence. I went upstairs to see if the prank, that costed the girl her life, worked. Leaving the basement and its stairs behind, I see the lights are off, and hear startled voices. Angered that the girl had died trying to play a trick on such beings, I try to find and kill them. The first I find is the butler, and I quickly electrocute and disintegrate him. The next I find is the lady friend, who ran, screaming, out of the house. Not without a few burns though. Sadly, the father saw the lady friend running out, and thought better of staying. He ran out shortly after.
The most angering, however, is that obviously the father didn't know his daughter was dead, and yet left her. I vowed revenge, staying in this house, roaming through the electronic items. Eventually, after a few decades, I forgot what he looked liked, so I scared anybody who came in.
Oh, but it got lonely. I just wanted to play with somebody. The girl's ghost didn't recognize me, and kept to herself. I came into a habit of wanting to play with travellers, not scare. I figured the father must be long dead, so I decided to give up. But sometimes, I think about how he just left, and how unfair it was that the girl had to die then.
I had no idea what to call what I had become, whatever electric thing it was. One day, however, a trainer whom I once again accidently scared away, dropped a strange red electronic device. I entered it and was blasted by trillions of facts and information. It felt like hours (and it might as well been) until it stopped. And after the boom of information, hearing more data inserted.
"Hey! Look, Infernape! That electric pokemon! Did you see it! It possesses electronics! Isn't that cool? Let's see what it is, Dexter!"
His boy's body and his Infernape were found a few days later, burned until they were almost unrecognizable. In his hand was a broken Pokedex, that only seemed to repeat one entry.
"Rotom: Its body is composed of plasma. It is known to infiltrate electronic devices and wreak havoc."