It's a game they play, sometimes.
(All the time.)
Jenny doesn't immediately grasp all of the rules, fluid as they are, communicated half through whispers, half through sly glances and meaningful looks, but she doesn't mind–she's a quick learner, and Clara is a good teacher.
(A very, very good teacher.)
They're lounging out by the TARDIS pool, when it happens; Jenny can't quite explain why, but this is the day she decides she's had enough of playing the student, at least for a little while. Today, she wants to lead the class.
Jenny looks up from her book–something about Critical Quantum Forces or Calibrating Crystal Fluxes or Causal Cats Fsomethingorother; it hardly makes a difference, since Jenny hasn't been paying attention to the book for quite some time now, not to mention she's holding it upside-down–and watches Clara as she lies supine on her pool chair, stretched out elegantly beneath the warmth of the artificial sun. Gentle golden light bathes the planes of her body, setting her skin aglow, kissing her hair, her cheeks, her lips.
(Jenny absolutely does not feel jealous of the light; that would be silly and irrational. In fact, she feels not-jealous all while she drops her book and walks over to Clara where she lies, and continues feeling not-jealous while she she straddles Clara on the pool chair, conveniently blocking the artificial light from reaching her.)
A mischievous smile plays across Clara's mouth and she opens her eyes, pushing her sunglasses atop her head. "Can I help you?" she asks.
Wordlessly, Jenny reaches down to the side of the chair. She finds a lever and pulls it, folding the chair to an upright position so that she and Clara are now face-to-face, Jenny perched neatly atop her lap, soaking in the heat of Clara's bare legs beneath her. Human beings are so delightfully warm.
Leaning forward so that their noses brush, then their lips, Jenny closes her eyes, enjoys the soft exhale of air from Clara's mouth to hers. She presses just the sweetest of featherlight kisses to Clara's cheek, the corner of her mouth, the tender pulsepoint beneath her jaw, lingering for only a moment before pulling away, ignoring Clara's faint whine of protest and how it pulls at something deep in her gut.
Jenny smiles. "No," she says sweetly, and moves to get up.
(She doesn't make it two inches before Clara pulls her down by the waistband, a silent plea for Jenny to teach her more.
Jenny is more than happy to oblige.)