Octavia, going on a rather extended tour with her orchestra, has charged Vinyl Scratch with the care of a human that she's been caring for: Anonymous. At his size, the ponies and their world is amazonian to him. Not only is the human smaller than Vinyl, but she must care for him until Octavia returns. Normally, something that wouldn't be a problem for a unicorn, but an accident from years past adds a strange twist to her endeavors.
I don't know, I suck at descriptions.