Brocken will need to perform the test with the only used pair around...

Broomi clenched her eyes tightly and fought back the heat rising to her face, a mix of embarrassment and a growing feeling of... something else... at the thought that her adopted brother had been cumming on her clothes for years and was about to get his hands on the holy grail of that exercise, so to speak. "Alright. We'll do it. But once we're done, I'm burning these ones. Knowing your spunk and my pee are on them is going to be too much for me," she resolved.

"Your habit?" Brocken muttered stupidly, as he watched Broomi reach down to the hem of her habit. His eyes widened as she began to lift it up to her waist... underneath, she was wearing a knee-length, thin, white under-robe... not particularly arousing, but still, not the type of thing one normally showed off to a boy.

"No, not the habit, stupid. Turn around..." she complained, as she sat down onto the bed. "Turn around!"

Her adopted brother spun around and clenched his hands on his knees, huddling them close to himself as his back faced his sister. Still... from this position, he could see just a bit reflected in the surface of the glass window. In that reflection, he saw the confessor reach beneath her under-robe and grab the side of her panties, then slide them down her legs. His demonic dick was throbbing, engorged and feeling fit to burst at any moment. "You're... You're going to let me-" he began, then cursed his stupidity. "You're going to make me cum in your panties?"

"Yeah... Just to see if it helps..." she murmured, stepping across the floor to set them down next to him. They were already a bit damp from her earlier scare. "Don't stare at them...!"

The boy was staring; being asked to try out the forbidden fruit, the one thing he'd always thought might give him some relief, but never dared attempt for the taboo of it, was almost too much. If he had to pick... he'd rather not use ones that she'd peed in... But he knew from the twitching of his dick that he didn't actually care that much. The panties were simple, white cotton with no frills and buttons near the waist... Broomi wasn't one much for fashion. As if worried that they'd disappear if he waited too long, he grabbed them up, ignoring the stain and hurriedly standing up to his feet. He lifted the pendant from his neck again, exposing his demon form... apparently, it was something he had to do in order to masturbate.

Broomi felt a twinge of disappointment at that... She'd kind of hoped-

"Kind of hoped what?! That you were going to see your human brother masturbate into your panties?!" Broomi thought to herself, slapping one cheek to expel the sinful thought from her head. "Adopted brother," another voice inside her head reminded herself, unwilling to let her be quite so prudish.

At any rate that form was clothed, while this form was buck naked. Realizing this, the incubus' face went from pink to red, and he gestured for Broomi to turn around. "Sis, don't watch!" he insisted, amusingly modest for someone with such a hedonistic appearance. Once she'd turned her back and crossed her arms... the situation fully sunk in to him. He was about to blast though these panties with his incubus semen. And... worse (better?)... his sister was standing in front of him with her under-robe exposed... and beneath that under-robe, she was going commando. As much as this test was supposed to help him get rid of that accursed erection, he felt like the anticipation of these indecent events was only strengthening it...

He looked from the panties to the seat of her under-robe and winced, feeling his cursed member demanding satisfaction. "Broomi... If... theoretically... I thought of something that might help the throbbing more than your panties... without hurting you, of course... Could I try it?" he questioned, going mad from the twitching of his erection.

"Well, sure... We're going to get that guy under control, one way or another, Brother Brocken," Broomi joked, trying to make light of the situation, even as she felt her own breathing quickening.