"I'm sorry I made you wait," said Chara, looking down on her kneeling brother with a mischievous smile. "But don't worry, we'll gonna have a lot of fun now."
Asriel gulps, continuing to look down, afraid to meet his sisters gaze. He knows well that Chara's idea of fun usually involves teasing and humiliating him. But this time he feels almost glad. Their last 'play' was two weeks ago and since then he wasn't allowed to cum even once.
The thought about possibility of relief makes his caged penis throb, painfully pressing against steel bars.
He swallows nervously, struggling to control his breathing. It takes every ounce of willpower for him to not start begging his sister to take off the chastity belt right here and now. But he knows better than to ask that. That would only make things worse...
Instead, Asriel focuses on the scenery around them. The waterfall looks like a gigantic marble pillar stretching high up above their heads, casting colorful shadows onto the walls behind them. Chara is sitting on the boulder on the edge of the lake, her bare feet splashing in the cold water while she smiles at him. His face blushes under white fur at the sight of her wet, bare toes.
"You're staring again!" she complains. "I thought you had more self-control than that!"
"Sorry..." he mumbles.
Chara's smile widens. She knows well how aroused Asriel is, and she has no plans of making it easier for him.
She take her foot out of water and lift it towards his muzzle, just a few inches away from his nose.
Asriel nervously lick his lips, unable to look away from his sister's foot. A small drops of water shine on her smooth skin, reflecting the light from the glowing gemstones in the cavern.
Despite his fear of being punished Asriel move his face forward and cautiously touches her toe with his lips. He clenches in fear, expecting a kick in the face or a burst of anger, instead Chara just let out a giggle.
"Aren't you getting brave to touch me without permission?" she ask teasingly and puts her other foot on Asriel's crotch making him wriggle and whimper.