Why wouldn't he want Cara to meet his sister? "Even if I didn't want you to, she'd bug me about it until I agreed anyway," he pointed. "It's just the way she is."
He smiled a bit. "It would," he agreed. "And I will." Oddly for now, he felt safer around Becky with Cara around. She would make sure nothing happened to his sister or Amy if he went crazy on them.