The Demon of the House of Hua (Those Who Break Chains Book 2) by Maria Ying

The sixth warlock of Hua sacrificed herself in a treacherous bargain, leaving behind her daughter to be raised by a demon... and her wife to deal with a household that has one infernal butler too many.

Madhuri, now mistress of the Hua estate, grieves for her lost warlock and grimly avoids the creature that's keeping her daughter alive. But they are full of surprises—they want to serve her in her lonely widowhood… and perhaps, slowly, court her for their own.

The Demon of the House of Hua is an F/NB gothic novelette (15,000 words) that explores the history of the Hua warlock line, and can be read as a standalone.