The wastelands near Sanctuary are a grim enough place, and it's always nice to have a little bit of color, glamour, and spectacle to liven up the land. Even if the color, glamour, and spectacle is as terrifying as Mistress Meena's Travelling Circus.
Mistress Meena appears human, but she's been around for hundreds of years. Probably since the Bieth fell. Her circus takes in the wretched, the poor, the dying, and those simply down on their luck. She doesn't flinch from the sick, the leprous, those twisted by the magic coursing through the wastelands.
That's because she changes them. She shapes their bodies, ripping and tearing, fusing metal and wire and wood to flesh and bone, and reweaves them into what she needs.
The acrobats that dash across the stage have springy spurs of bone emerging from their calves, allowing them to bounce and bob with the utmost dexterity. When they spread their arms wide, the scarlet, pink, and blue ribbons stretch from their arms down to their ribcage.
The clowns have had the color bleached out of their skin and concentrated into their hair and nose, their lips swollen comically, their eyes cartoonishly large.
The harp that plays itself has a human head, with golden tresses, and she sings to accompany herself. The graceful arc of the harp's body used to be her spine. Arms and legs, she has none. The trapezes used to be two lovers, and now they come close each night but never touch.
Mistress Meena seems to be the only unshaped person in the circus. She never doffs her black domino mask.
The circus caravan proceeds through the worst parts of the wasteland. They never turn aside, and never seem to be molested by the wild creatures or bandits.
When the circus comes, you do not turn it away. Once in a while someone from an outlying village, or even Sanctuary or Lithquil, will approach Mistress Meena after the show. She will smile kindly, and touch their arm, and lead them away. Sometimes their friends see them again, changed into another component of Mistress Meena's show. If they do, they always regret it.
Think: Freaky batshit John Blanche art, travelling circuses, and Alistair Reynolds's Diamond Dogs with a creepy-ass Zatanna as Dr. Trintignant.
(Disclaimer: idea cribbed from a description of the Circus Tresaulti I heard, but I haven't read any of the stories yet.)
Relevant quote from the Amazon preview: "Their dancing names are Sunyat and Sola, Moonlight and Minette. (Their real names don't matter; no one in the circus is real anymore.)"