Zinka Fearon is a pleasant, plump, extremely intelligent lady who is also a Magid. She is known to protagonist Rupert Venables, who is surprised to see her at the Phantasmacon convention, but she is similarly surprised to see him, since she comes to this convention every year and sells art pieces there, putting all her affairs on a waiting status, and just vacationing and having fun.
She appears first when she is rescuing poor Maree Mallory from the dark psychic clouds and unwanted hand massages of Tansy-Ann Fisk, who Zinka evidently knows from way back. She then tells Rupert that she is not at the convention to help him out with whatever his current working is about, because she can tell it isn't that critical. She does, however, say that she'll help if a crisis comes up, and soon enough, one does and she helps.
She is a wonderful character, one you wish you knew in real life. The surprise that comes up near the very end of the novel is just icing on the yummy chocolate sponge cake of her awesome personality.