After hearing their current Great Lord is dead, Clara (along with four other young women) is snatched off the streets of Everdark and taken to the citadel where the kingdom's newest Great Lord, Lucias. Unlucky enough to be chosen from the group, she discovers that she's there because their Great Lord is in need of an heir. She's having none of it, though and tries to flee before learning that Lenora of Ne'ermore, an old enemy and ex-prisoner of their kingdom, is dead set on slaughtering Lucias... and Clara. Oh, and if Lucias dies heirless, his army will terrorise her beloved home, leaving Clara caught between regaining her freedom or losing it for the good of the kingdom.
Dark One's Mistress contains examples of:
- A Hero to His Hometown: Lucias to everyone inside of his kingdom.
- Almost Kiss: This is initiated by either side several times throughout the book.
- Army of Thieves and Whores: The Dark One's army is literally made of criminals. They're also The Soulless.
- Attempted Rape: A random guard with Clara.
- Bad Powers, Good People: Lucias can steal souls and brainwash people, but only uses either ability on criminals.
- Belligerent Sexual Tension: Lucias and Clara. Practically right off the bat when they first meet as she's trying to escape his notice.
- Big "NO!": Lucias when Clara is about to be stabbed.
- Black Speech: Both the soul-stealing and Brainwashed spell come out as a guttural, garbled mess that pulls at those who hear it.
- Boy Meets Girl/Meet Cute: Lucias meeting Clara.
- Brainwashed: What is Lucias' reaction to a guard trying to rape Clara? Take over the guy's mind and convince him to kill himself via climbing a tower and jumping out the window.
- Child by Rape: Essentially how Lucias was conceived.
- Conscience Makes You Go Back: Clara when she's about to regain her freedom and learns a young homeless kid has been captured along with some criminals.
- Deceased Parents Are the Best: Whilst both main characters are missing their fathers, Clara has far fonder memories of her dead father than her still-alive mother.
- Defiant Captive: Initially, Clara refuses her title as the Great Lord's mistress and makes numerous escape attempts.
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Designated Villain: Lucias to everyone outside of his kingdom. Partly justified in that he's kingdom has invaded their neighbours in the past, but given that his father was the ruler until the beginning of the story, this is likely inherited resentment.- Although, the whole soul-stealing thing his family does probably doesn't help.
- Destination Defenestration: The fate of the guard who tried to rape Clara.
- Dirty Old Man: Count Farris. When reminded his young fiancée bears the surname Goodheart, his response is: "I do hope she's not too good, eh?"
- Dying Declaration of Love: Lucias to Clara.
- Geometric Magic: The fortress dungeon in has a circle of glyphs embedded in the floor, these glow when Lucias uses Black Speech and are apparently necessary for him to steal souls, but not leave people momentarily Brainwashed.
- Grey-and-Gray Morality: The Dark One of the title uses criminals in the royal army, keeping them leashed by way of stealing their souls. Innocent people sometimes get caught in this web and while killing him off is the only way to free them, it would basically unleash hell on the populous.
- Groin Attack: Clara attempts this several times over the course of the story (Lucias, her would-be rapist, and the barbarian). She succeeded with her the third target.
- Heir Club for Men: Lucias' need to produce a child.
- I'm Not Hungry: Clara's third act of defiance. When that fails, she falls back to escape.
- Interrupted Suicide: One of Lenora's efforts to rid herself of Lucias whilst she's still pregnant with him.
- Knight Templar: Lenora given her "must kill the Great Lord no matter what" stance.
- May–December Romance: Count Farris is somewhere in his seventies and planning on marrying eighteen-year-old Brenna Goodheart.
- Pillow Pistol: Lucias sleeps with a dagger beneath his pillow.
- Sword Fight: Lucias up against the barbarian in the end. Although that's more a sword vs sword and battleaxe.
- The Soulless: Lucias' army. All of them.
- Well-Intentioned Extremist: Lenora's dead set on killing her son, seems unconcerned that this will lead to a lot of civilian deaths.
- Your Soul Is Mine!: How Lucias' army is really made.
