'Tandem dream'? That sounds like a fake thing. Or a plot contrivance to make soul mates, or mortal enemies, meet before they finally encounter each other in reality. Which is... surely not the case.

"Nyeh! Heh heh heh! See that, you can't!" He laughs triumphantly, then gestures at Xanxus to follow him. "But don't worry, dream person. I am a benevolent skeleton! I could treat you to dinner while waiting to wake up."