Playwright Cori Thomas was changing subway trains in Times Square a few years ago when she saw a scene that made a big impression on her. Two women of similar age, one clearly disabled and black, the other her white caretaker, were gently interacting.

"What was so interesting to me was how genuine their affection was," said Thomas. "For the caretaker, it wasn't just a job. I was so fascinated by their relationship, I almost followed them."

The scene stayed with Thomas. She is accustomed to seeing black caretakers of whites, she said -- think of "Driving Miss Daisy" or "The Help" -- but not the reverse. She tried to answer the many questions arising from the scene by writing a play. The result, "My Secret Language of Wishes," is about unconditional love, race and a broad sense of family. The play's central conflict revolves around an adoption battle between a mature, middle-class black woman and a younger white woman over a young black woman with cerebral palsy.

"That's often how a play starts with me -- I have some question or issue that I have to work out," Thomas said.

Directed by Obie Award-winner Marion McClinton (who also staged Thomas' "Pa's Hat," a few seasons ago at Pillsbury House Theatre), "Secret Language of Wishes" is one of three works running concurrently in Mixed Blood Theatre's "Center of the Margins" festival, which opens today in Minneapolis. It features such actors as Jevetta Steele, Mo Perry, Nora Montañez, Signe Harriday and Brittany Bradford.

The festival, which explores "the complex world of disability," puts Mixed Blood in the theatrical bull's-eye again.

The theater recently closed "Neighbors," a play that provocatively deployed racist stereotypes.

For Jack Reuler, whose founding vision for Mixed Blood anchored it in the Rev. Martin Luther King's inclusive dream, the festival is part of an attempt to catch up with the disability-focused Interact Theater.

"In 2000, I went to Interact for the first time and saw a theater that looked like what I wanted Mixed Blood to look like," he said. "It ran the racial and cultural spectrum, with people of all ages and disabilities working together. I was inspired with envy."

In all, the three plays will have a total of 40 alternating performances through Nov. 27. The other two works to be performed at Mixed Blood during this festival are Rajiv Joseph's "Gruesome Playground Injuries" and Ken LaZebnik's autism-themed "On the Spectrum," a Mixed Blood commission.

Exploring power of pain

For Joseph, whose "Bengal Tiger at the Baghdad Zoo" was headlined by Robin Williams on Broadway, "Gruesome" is part of an exploration of the "transformative powers of pain and violence." The idea arose after some carousing with a chum, Joseph said by e-mail.

"He began telling me about the insane injuries he'd endured over the course of his whole life," said Joseph. "They were hilarious and horrible. ... I speculated he could name each chapter of his memoirs after an injury."

In "Gruesome," directed by Aditi Kapil, two people who meet in the nurse's office at school mark their growth together over three decades through their wounds. Mixed Blood has cast two deaf actors, Alexandria Wailes and Nic Zapko, as the couple. The two women will deliver their dialogue in American Sign Language. It will also have surtitles.

"That's a way of dealing with what is normative," said Reuler.

A similar ground-shifting also happens in "On the Spectrum," in which two of the three characters have autism. The play was sparked by intense online discussions about whether autism is a disability or merely a neurological difference. That is the central question of "Spectrum," in which a young man with Asperger's syndrome falls in love with a woman who "passes for neurotypical," said playwright LaZebnik, a Los Angeles-based TV writer who once wrote for "A Prairie Home Companion."

The subject is personal, said LaZebnik, who went to Macalester College with Reuler and has written three plays in recent years on autism, including "Vestibular Sense."

He has family members who are on the autism spectrum.

Even as he explores autism -- he suggested as the lead for his play California-based autistic actor Laura Robinson, who is joined in the cast by Ivey Award-winner Regina Marie Williams -- the playwright fears being misconstrued by the community that he is championing.

"The autism spectrum is so vast, I hope that people with families on [it] will accept this as the story of two individuals," LaZebnik said. "I'll never be able to dramatize the situation of everyone. I can only dramatize the situation of these two fictional characters trying to find love, and to answer some hard questions."

That's true of all the plays in a festival where things that happen in the shadowy margins are brightly lit on center stage.