Sister Light, Sister Dark, by Jane Yolen (fantasy novel, 1988)

[lb_lee]

As if in a trance, Jenna stepped forward until she was almost on top of the mirror. Palms out, she placed her hands upon the glass. Instead of the hard surface, her hands touched warm skin, palm to palm. She closed her fingers about the image's fingers and drew the other from the glass.

"It took you long enough," said the image. "I could have been here days ago."
"Who are you?" Jenna asked.
"Your dark sister, of course."

Blurb: (from Uranian Worlds) Combining legend, song, and storytelling, the first book in the author's Great Alta series unfolds a prophecy of young Jenna, who will bring about the end of matriarchy and the beginning of something new. Jenna comes from the all-women Hames, where at puberty they draw their "dark sisters" from the mirror to be their eternal companions who only appear by moonlight or torchlight.

Why is it worth your time?: The dark sister is a very cool idea! Even though Jenna's dark sister claims that she IS Jenna, just another side of her, it's clear from other characters that the sisters can have disagreements (sometimes very cruel ones), that one can mistreat another, and so on. Otherwise it is straightforward high fantasy of mythology, Chosen Ones and heroes. (Also, because I came in hoping for girl-smooching: there is no girl-smooching in this book. Sorry.) This book more concerns Jenna's upbringing and childhood; the epic plot comes in later.

Plural/1+ Tags: abuse not mentioned, identityblending, intimate relationships, setting-specific

Content Warnings: high fantasy level adventure, peril, and violence. More contain spoilers; see comments.

Accessibility Notes: See the tag list for examples. Also note how you can get it. Is it an easy library book? Has someone digitized it and put it elsewhere? Is it backed up anywhere? Is it available in other languages than English?

Misc. Notes (if any): first book of a series; the second is White Jenna, which I didn't finish because Chosen One hero cycles really aren't my thing, and the One-Armed Queen, which apparently doesn't have the dark sister angle. Available on paper and ebook, and also in the omnibuses The Books of Great Alta and the Great Alta Saga.