Use a Buttplug on him

“Can't leave this greedy hole like this though, knowing the kind of horny girl you are you would no doubt play with it all day,” she punctuated her words by squeezing a rubbery pink buttplug into his ass, the widest part significantly thicker than the two fingers she had used earlier. Harry groaned as she pushed it in, gasping softly when it popped past his sphincter, the flat base resting tight against his hole.

"It's charmed you see, you can't touch it even if you'd like to, prevents you from being naughty. Don't worry about having to run to the toilet, it will vanish any waste,” Bellatrix seemed inordinately proud of her creation, her voice almost giggly as her fingers adjusted it so it sat perfectly. Pleased with her work she pulled him up, making Harry disgruntled at how easily she was handling his small frame.

"One last touch,” she murmured, bringing her wand to his crotch. Harry froze in fear, knowing her it might be anything from a cutting to a burning hex. Instead Bellatrix did an elegant twirl, forming a smooth black cage around his softened cock, trapping it tightly in its flaccid state while still leaving him space to relieve himself. She also threw a quick cleaning charm, removing the cum he had splattered all over himself and her robes.

"Why are you doing this Mistress Bellatrix?" He murmured, looking down at his hairless trapped genitals. He didn't mean the chastity device, which she obviously understood.

"Because the Dark Lord decided to let me have you,” seeing his surprised look she smiled, adjusting the cage to make sure it was secure.

"After the whole Ministry debacle Master returned in deep contemplation before declaring that you were not to be killed under any circumstances. I asked if I could have you instead, an idea he seemed to find amusing, so he granted me that wish,” Bellatrix smiled, her eyes shining with devotion for her master.

Satisfied with her work she stood up, easily towering over Harry. He had always been the shortest boy in his year and her stately appearance just made him feel smaller. "How did you capture me Mistress Bellatrix?" he asked **** for information.

"First I had to wait outside of King's Cross Station with an invisibility cloak until you walked out, then I followed you and those muggles on a broom until you stopped at some lights in that car thing. A muggle repelling charm on my broom, a stunning charm in your face and a quick Obliviate on the muggles was all it took. They didn't even realize you were gone until weeks later,” She laughed at the ease with which she had kidnapped him, leaving Harry gaping.

"Now," she said, "it's time for you to get dressed for dinner."

Eating was the last thing on his mind and he gave her a mutinous look.

"Please," she snorted, "don't bother with some protesting ridiculousness, if you attempt to starve yourself I will just Imperio you and **** you to eat. And yes, I know you barely resisted the spell when cast by Barty, but don't make the mistake of comparing his pitiful power to mine."

His defiant stance shrunk at her words. She was known as the most dangerous and sadistic of Voldemort's followers for a reason, he had no doubt she could make him eat if she wanted to.

"Oh and no silly thoughts about throwing up the food, I've already taken care of that pesky gag reflex of yours, though for very different reasons,” she giggled.

She ignored his questioning look and enlarged a box she pulled from her pocket, throwing it on his makeshift bed.

"There are your clothes, I expect you in the Dining Hall in fifteen minutes,” she conjured a large mirror on the wall for him to use as she walked towards the door. Turning back in the doorway she gave his nude form one last appreciative glance.

"Should you not show up fully dressed in time, I will be most disappointed,” she ended the sentence with a dangerous look that made him audibly gulp.