The Governess Affair by Courtney Milan

Hugo Marshall earned the nickname "the Wolf of Clermont" for his ruthless ambition--a characteristic that has served him well, elevating the coal miner's son to the right hand man of a duke. When he's ordered to get rid of a pestering governess by fair means or foul, it's just another day at work.

But after everything Miss Serena Barton has been through at the hands of his employer, she is determined to make him pay. She won't let anyone stop her--not even the man that all of London fears. They might call Hugo Marshall the Wolf of Clermont, but even wolves can be brought to heel...

The books in the Brothers Sinister series:
½. The Governess Affair (prequel novella)
1. The Duchess War
1½. A Kiss for Midwinter (a companion novella to The Duchess War)
2. The Heiress Effect
3. The Countess Conspiracy
4. The Mistress Rebellion