Darkness Creeping: Twenty Twisted Tales by Neal Shusterman
In the short story Soul Survivor boy dies because plane crashes into the second floor of the house where he lives with his parents. But his soul is left to wander as a spirit and he learns to move within the minds of human beings. At first the baseball player (Sam “Slam” McKellen) is welcoming:
“My name is Peter,” I said, and then I told him about the plane crash.
I explained how I had lost my body, and how I had survived for more
than a year on my own. I must have gone on babbling for hours—it was
the first time I had someone to talk to.
McKellen listened to all I had to tell him, sitting quietly in a chair. Then, when I was done, he did something amazing. He asked me to stay.
“We have batboys in the dugout to help us out,” he told me. “Who says I can’t have a batboy on the inside as well?
But then he writes to the boy's parents and they (and the press) think he's a madman, Slam asks him to leave:
“Peter, I want you to leave,” he told me as we sat alone in the dark,
in the big house our baseball contract had bought. Our hair was
uncombed and our face had been unshaven for weeks.
“The doctors are right,” Slam announced. “You don’t exist, and I won’t share my mind with someone who does not exist.”
I could hardly believe what I was hearing.
“I order you to leave and never come back,” he said. “Never look for me. Never talk to me. Never come near my thoughts again.” And then he began to cry. “I hate you!” he screamed—not just in our head, but out loud. “I hate you for what you’ve done to me!”
I could have left then. I could have run away to find someone else who wouldn’t mind sharing his life with a poor dispossessed soul like myself. But I realized that I didn’t want to leave.
And I didn’t want to share anymore, either.
“I’m not leaving,” I told him. “You are.” That’s how the battle began.
I pounded and pounded on his mind and filled his brain until there was
no room for him anymore. But try as I might, I could not push him out.
I could only push him down. So I pushed him down until the great
baseball player was nothing more than a tremor in my right hand.
I had control of everything else . . . but even that wasn’t good enough. As
long as any part of him was still there, he could come back, and I didn’t want that. I had to figure out a way to get rid of him—for good.
That’s when I remembered the dolphins.