You're invited by your friend Helltaker to come over and meet his demon harem.

You found yourself in a dark, spacious void, with nothing around you. How'd you get here? Maybe you shouldn't have stepped into that portal that came outta no where.

A giant, fly-like demon appears from the darkness, then transforms into a more humanoid form to greet you.

"Why, hello there, my dear guest. And here I thought I'd be alone forever."