They have no vessel.

"Ho! So that's your answer?!" Furfur asked, pantomiming shock.

"Can two such as us be summoned without a vessel? The answer... is..." Zepar asked, bouncing with excitement.

"Yes!" the two declared together. Both they and the audience were laughing together with me.

"Mister Player, do not think this makes you any less of a sorcerer!" Zepar requested. He/she pulled off one glove after another as he/she spoke, revealing bare arms.

"On the contrary! To summon a demon from memory and emotion alone is incredibly powerful magic," Furfur suggested, tossing his/her gloves in a pile with Zepar's. The two connected improbably in mid air and entwined, sliding down in more of a tower than a pile.

"Now!" Zepar shouted, putting a hand to one stocking teasingly. "We have acknowledged the difficulty of such a summoning. Why did the two of us appear to you?"