Cotton Cloud is Mad Cloak's Real name. She was disowned by her family (for plotting to overthrow Princess Celestia) and they attempted to lock her away in a mental health facility so Cotton Cloud bolted, created a new identity for herself and eventually wound up in ponyville.
Well what happens in Las Pegasus stays on a marriage certificate!!!!!! Had a bit too much cider did we Cotton Cloud? Well hey you got Derpy!!!!! There's many a Stallion back in Ponyville that will be jealous of you now! Poor Derpy though.....she looks like she doesn't even know what hit her! Bravo Stardust! And Bravo Hazura-chan! You've really brought the story of Mad Cloak and Stardust to life here!
Well Mad Cloak and Derpy were gonna wind up together but me and Stardust decided that it would be so much more awesome if we did it this way with Mad Cloak and Derpy being drunk off their flanks and Stardust getting them married (originally it was gonna be a prank wedding as in Stardust hires a fake priest but it turned out to be a real priest and so on etc.)