Until he couldn't take it anymore. Well she had her instruction, she thought as long fingers that just recently had done so much for her curled into her hair as his other hand reached out to find support, she was almost flattered. But then she really was just that good.
She hadn't taken him fully yet. Ruby was taking her time, relishing the challenge, loving the look in his eyes, the utter desperation she was invoking in him, until he couldn't take it anymore, thats what he wanted from her so thats what he'd get.
Her expert tongue wrapped around, running along him, flicking out occasionally to drive him crazy until finally she knew he was ready. She took him, all of him, deep inside her throat, sometimes being a demon and having the ability to forgo breathing had its upsides, she could do things to him, go longer than anyone else could. She kept up a steady rythem as his hand tightened in her hair. She'd keep it up until he was ready, until he couldn't take it anymore and then she suspected he'd pull her back, maybe throw her on the bed, rough like they enjoyed. Take her for himself. Make her his.