He's seen the looks she gives Ethan when she thinks he's not looking. Caught the same directed at him more than once. Considering how closely they work together, and the teenage hormones that she was only just starting to learn to cope with when they met, it's not a surprise.
Perhaps, if he were a better man, the man his family expected him to be twenty years ago, he would ignore it. Would rebuff her and find someone younger and more appropriate to redirect her attention to. If he were that man, the one he ran away from being and never looked back.
Who he is, Ripper, has no qualms about encouraging her interest. Leaving doors unlocked for her to wander in at the wrong (right) moment, whether it's him and Ethan shagging, or just himself having a leisurely wank. A hand lingering a heartbeat longer than needed when correcting her, walking closer than propriety would demand when escorting her to any one of the lectures and exhibits that she wants to share with him.
Only when she asks, curious instead of embarrassed, does he offer her more than glimpses and fleeting touches. Still not what she's looking for, but even she's not worth the risk of a stint in the gaol. That anyone with a passing knowledge of magic would hope what he's showing her is illegal doesn't actually mean anything.
She arches under his touch, trying to shift so his hand slide further down her jumper-clad torso, and he chuckles, sliding it around and up her back instead, letting the magic spark and warm, running along her nerves. Bringing his other hand up to rest them on her shoulders, thumbs rubbing small circles at the base of her neck, close to her spine.
"Ripper!" She draws out his name, pleading for more than he's willing to give her, and he shakes his head, leaning closer to whisper in her ear.
"Patience, Willow. Six more months, and you can ask me again."
She shivers, whimpering, and he sends another pulse of magic along her nerves, watching her arch and moan. Letting magic curl and caress as she leans back against him, eyes closed so she can focus on the sensations dancing across her skin. Keeping his hands tracing lines that stop just shy of anywhere inappropriate. Skating along the razor's edge.
He traces the tips of his fingers lightly around her hips and up her spine, drawing the magic with him, and pulling a shuddering gasp from her. Her body tenses, eyes screwed tightly shut, heels digging into the couch as she rides the crest of oblivion, before falling back panting.
He shifts so she's curled against his side, one arm wrapped around her shoulders as she cuddles against him, twitching slightly with the aftershocks. It isn't what she'd asked for, but he's always found that sensory overload is the same, no matter if it comes from magic or pain or pleasure.
"Where is that from?" Her voice is still shaky, and he strokes a soothing hand along her arm a moment. She's looking at the shelves that are visible through the door to his and Ethan's room.
"Not from any book, Willow." He meets her gaze with a gentle smile, reminding her quietly, "Six months."
"Yeah." She grimaces a moment before smiling at him again. "Six months. If I don't pick up sooner."
He chuckles, pressing a brief kiss to the top of her head. Even if she does pick it up, he knows she'll be back for more.