Eddie Riggs had just a few errands to run. Just a few, that's all. Once he was done, he could get back to Ophelia and teach her the finer subtleties of French Kissing.
At the exact same moment, in another world entirely, Discord decides he needs a vacation.
Cue Eddie Riggs, the Ultimate Roadie, needing to get used to some of the most non-Metal things in existence, and some of the most non-Metal things in existence needing to get accustomed to the Ultimate Roadie, Eddie Riggs.

(Knowledge of Brütal Legend is necessary to understand many things in this story. Heed my warning; ignorance of the source material will result in becoming lost)