The suggestion that he'd do anything she'd been somewhat expecting after the other things he'd said this evening, the lack of knowledge of the colour system was a toss up since not everyone used it and it was based on muggle traffic lights anyway (and she had no idea if he had a muggle parent or not, and there was no way he drove given his condition), but the lack of knowledge of safewords made her hold onto a suddenly fierce growl that was trying to escape her throat. She sucked in a deep and horrified breath and had to consciously let it go as slowly as possible so she didn't lose her temper. The hand on his face had twitched slightly, the points of pressure in her fingertips increasing as she wanted to curl her hand into a fist, but gone in an instant. If she ever found out who had slept with him without even the most basic safety concerns (and reading between the lines a lot less than that), let's just say they would find out just how good Gwenog Jones' transfiguration spells were.
She took a second breath, slow and steady, trying to make sure any anger that had appeared faded from her face. She had no anger at him. "No see there's a difference between not minding, and liking. The colours don't matter too much, it's just a way of checking in that everything is okay. But knowing what you like and a safeword are really important," she said gently, but firmly. "Come on, we should sit for this," she said, sliding her hand down to his shoulder and guiding him to the sofa. She sat herself, not losing touch with him, gesturing for him to sit too.
She summoned two glasses and spelled water into them. They would be needed later anyway. She moved so their nearest knees were pressed together and let her hand drop away. "A safeword is what it sounds like. Its something that makes you safe. It's a word you use to tell the person you're with that you need them to stop and stop right now because what they're doing is something you don't enjoy. It might be something like not liking being blindfolded, or maybe you don't mind your hands being bound but not your feet. It's something that keeps me safe too. I don't want to be doing anything that you're not enjoying," she explained. "I don't mean in the way that someone who enjoys being spanked will still feel the pain, because they enjoy it and it will also feel good in a way. I mean that somebody who has had a bad experience with..." she paused casting around for something not specific to anyone in particular. "Someone that's had a broken ankle at some point and hates pain near their feet wouldn't want to be hurt there. If someone they were with started to do something to their feet they could say their safeword and that person would stop right away."
"And you don't have to like everything. Nobody likes everything, and definitely not to the same degree. For example I hate cutting anybody, I never use knives or needles. I rarely have the patience to tie someone up in complicated rope scenes." She was wary of telling him things she did like, worried that he'd say all the same things just to please her. She didn't want that. "I want to find out what you like, because this is all about making you feel good, maybe make the world fall away in that special way." She hesitated for a moment before continuing. "I noticed you seemed to like it when I praised you earlier. Did that feel good?"
She had a feeling her explanation was a bit ham-fisted, but she'd never had to do this before, at least not with someone who she thought had previous experience of kink.