Have you ever met somepony who claims they can hear another voice in there head besides their own? How about that they're sharing their body with another being entirely? No? Well then you haven't met Vinyl Scratch.
Octavia is having a quiet afternoon alone and decides to eat the last of Vinyl's pudding cups. Doing so is more difficult than she expects. Especially when Vinyl time-travels back from a dark, apocalypic future to stop her.