She can suck on something else.

If you let her suck your cock, you doubt that Selas will let you go without taking almost everything from you, leaving you to deal with your guest on an empty tank. But, channeling more power to your fingers, you shove a couple of them into her mouth.

She takes them in graciously and starts sucking furiously. Her tongue wraps itself around your digits and starts to creep it's way past them. Shifting your grip, you press your palm against the underside of her chin and start to squeeze her tongue between your fingers. Selas shivers in your grip, and her tongue retracts back with a snap. Her hand comes up and takes hold of your wrist, while her eyes shut in blissful satisfaction. Her tail also wraps around your ankle and almost affectionately strokes it. Keeping a careful watch on your stock, you feed her as much as you dare, pulling your fingers free when you feel like you've hit your limit.

Selas lets out a long shaky breath, that travels through her entire body and hangs her head. Her pupils thin into narrow slits and she glares at you. "After tomorrow... recharge... all mine. All. Mine." she snarls. You swallow nervously and nod. You don't get any sleep that night. Not with Selas crouched in the corner of your room, growling hungrily at you. The meager scraps you've given her, barely enough to satiate her.

The next day, she seems to be closer to her usual self, if a bit more frantic. With your furniture out of the way, she directs you to paint out a complex series of symbols and runic letters, in a massive circle, on your living room floor, making you redo the whole thing if you are a degree off. There's a distinct copper-like smell to the red paint, but you'd rather not know where this paint came from. It takes all morning, but eventually, Selas is satisfied with the circle. "Now what?" you ask, stashing the brush and bucket under your table.

"Now, we wait." she swallows, keeping her eyes focused on the circle. You grunt grimly, find your couch, sit in it, and wait.

Hours pass, and Selas has not moved a muscle. Not even a blink. When evening came around, you tried poking and prodding her, but no reaction either. Shrugging, you duck into the kitchen to figure out what you can make for dinner, when you hear your doorbell ring.