Catherine waited for him to explain, but Isaac simply smiled.
He was waiting for her to ask how he could do it.
The two of them had always engaged in war of wits. Neither liked giving ground, and both constantly looked for opportunities to gain an upper hand.
Right now, Isaac was openly showing that he wanted Catherine to ask him for something. If she did, then he would have won this round.
Catherine stared at him for several seconds before finally caving in.
"How can you increase my strength?" Catherine asked.
Isaac's smile widened slightly.
"That's a secret. But first, let's talk about payment. I need to go to huge lengths to give you a boost that can make you five times stronger. Since I'm doing so much, surely I will get an appropriate payment?"
The way he emphasized the word payment made his meaning obvious.
Catherine raised an eyebrow.
"Since when did my little brother become so bold?"
"Since I conquered you in bed," he answered with a smile.
