Who said "In my wars, I've learned that mercy is the first casualty."?

This quote is attributed to Ramsay Bolton.

In my wars, I've learned that mercy is the first casualty. - Ramsay Bolton

"In my wars, I've learned that mercy is the first casualty."

Ramsay Bolton War

"I am the master of my fate. I answer to no one."

"If you think this has a happy ending, you haven't been paying attention."

"A man who must say 'I am the king' is no true king."

"You're a slow learner, but you do learn."

"Some battles are worth fighting."

"Sometimes you have to become the monster to stop the monsters."

"Skynet sent me back through time to kill you."

"War teaches us the value of peace."