The onion girl / Charles de Lint.

Enhanced descriptions from Syndetics:

In novel after novel, and story after story, Charles de Lint has brought an entire imaginary North American city to vivid life. Newford: where magic lights dark streets; where myths walk clothed in modern shapes; where a broad cast of extraordinary and affecting people work to keep the whole world turning.

At the center of all the entwined lives in Newford stands a young artist named Jilly Coppercorn, with her tangled hair, her paint-splattered jeans, a smile perpetually on her lips--Jilly, whose paintings capture the hidden beings that dwell in the city's shadows. Now, at last, de Lint tells Jilly's own story...for behind the painter's fey charm lies a dark secret and a past she's labored to forget. And that past is coming to claim her now.

"I'm the onion girl," Jilly Coppercorn says. "Pull back the layers of my life, and you won't find anything at the core. Just a broken child. A hollow girl." She's very, very good at running. But life has just forced Jilly to stop.