Junk in the Trunk- Millie (Helluva Boss)

                                    

                                          
As requested by Dragonsw! Male Y/N.
Millie laid her head on her husband's chest on the couch in the IMP office. Blitzo and Moxxie were out on a job, and Loona was sleeping at her desk, so the pair had some alone time. Suddenly, Millie's stomach growled.
Y/N glanced down at her and smiled. "Hungry?"
She chuckled. "A little bit. I'll be right back." She climbed off the couch and went out into the break room. Millie's eyes widened when she saw a box of her favourite cookies on a shelf above the counter. She stood on her tiptoes and stretched as far as she could, hopping up a bit to try and reach them. But alas, she was too short.
"Ouch," she winced, pulling back as she felt as though she'd overextended her arm. Millie glanced back to the living room, where Y/N was scrolling on his phone, waiting for her. He was a humanoid succubus, so he was pretty tall for a demon. He could easily reach the cookies.
But being as stubborn as she was, Millie was not about to ask for help. She looked around the room and found a few boxes of Blitzo's random crap in the corner of the break room. Smiling, she went over to them and brought them to the counter beside the shelf.
Millie stacked them precariously, but she was sure it was stable enough for her. Tentatively, she stepped up onto the first box, then the second, then the third...
But she wobbled on the third ox a bit too much and her structure came tumbling down. She landed on top of it with a crash.
"Mils, are you okay in there?" Y/N asked, glancing up from his phone. He saw her on top of the boxes and frowned. "What are you doing?"
"I uhm, thought Blitz might've had some of those snacks I liked... guess not," Millie answered, rubbing the back of her neck sheepishly.
Y/N raised his eyebrow, not sure that was what she had been doing. But stranger things have happened before. Shaking his head, he went back to his phone.
Millie exhaled defeatedly and looked down at her hands. But she saw a glint out of the corner of her eye and glanced up to see her axe sitting by the fridge. She grinned as she got an idea.
Grabbing her axe, Millie rushed to the other side of the room, opposite the shelf with the cookies. She lifted the axe high above her head and sprinted toward the cookies, stopping partway there to launch herself into the air, like she was pole vaulting.
She laughed as she saw the cookies become within her reach, but it quickly died down when she realised she had launched herself too high, and wasn't stopping. She was about to slam into the cabinets above the shelf when suddenly, Millie felt herself stop in midair.
"If you wanted these, you could've just asked," Y/N told Millie, holding up the cookie box as he had his arm wrapped securely around her waist. He placed her down and handed her the box.
Millie smiled and took it, thanking Y/N, but she couldn't help but feel a little insecure. She was only about as tall as her husband's midriff, and she hated having to ask him for help all the time to reach things that she couldn't. Although it didn't bother Y/N in the slightest- in fact, he found it cute- it annoyed Millie a lot. She loved having Y/N to depend on but also wanted to be independent as well.
Millie walked with Y/N back out to the couch and sat beside him, opening the box of cookies and shoving one in her mouth. She cuddled back into him like she was before and he stroked her hair.
Loona suddenly let out a loud snore, and the pair looked over at the hellhound, who was dead asleep. "I told her not to drink three bottles last night," Y/N laughed, shaking his head.
But Millie didn't respond, she was too busy gazing at the Grimoire that Loona was sleeping on. A book of spells, all kinds of spells... even spells to make her taller... Smirking, Millie got an idea.
"Honey, I need to go to the restroom, would you excuse me?" she said, slipping out of his grip.
Y/N pouted slightly. "Well, okay. Come back soon, I want more snuggles."
Millie winked. "Don't worry, I will." As she walked by Loona's desk, Millie discreetly snatched the Grimoire from her and brought it into the lavatory with her.
Millie sat cross-legged on the floor and flipped through the book, finally finding the spell she wanted, a growth spell. She clapped her hands. "Ooh, this is so exciting! Y/N will be so surprised!"
The pronunciation of the spell was difficult, but Millie was sure she could do it. She recited the spell quickly and then ran to the mirror to watch the results.
At first, nothing happened, and Millie wasn't sure if she had even activated the spell. But suddenly, she felt her ass get heavier. She gasped and turned slightly in the mirror to see that it was growing!
It almost doubled in size, stretching her pants to make them extremely form-fitting. "No, no, no!" she exclaimed, going back to the Grimoire. "Ugh, I should've practised it!" Tears pricked her vision as she reread the spell.
"Well, well, well... I can see what's taking you so long," Y/N drawled from the doorway. "I like this..." Millie glanced up at Y/N through her hair, but Y/N could still see that she was fighting back tears. "Oh no, Mils, don't cry. Tell me what's wrong." He said, kneeling beside her.
"I was supposed to grow taller," she explained with a shaky voice. "But instead, well, you saw." Millie pointed to her ass and blushed profusely.
Y/N gently placed his hand on it and moved it around her new, voluptuous ass. Her curves felt perfect under his hand and he had to admit, he found it sexy.
"It's hideous," Millie muttered, shaking her head disappointed.
"Well, the way I see it..." Y/N turned her around and cupped her cheek in his hand. "Now there is more of you to love."
Millie seemed surprised at this and smiled softly. "You don't think it's ugly."
Y/N chuckled. "Quite the opposite. I love it." He gave her bottom a light smack, watching it bounce. "We are going to have so much fun later tonight."
Millie grinned widely and hugged him. "I'm so glad you like it! Maybe this won't be half bad!"
Y/N picked her up and kissed her passionately, digging his hands into her hair. "Definitely not. Although, you might need some better-fitting pants. I don't need everyone staring at you when we go out."
"Yeah... I don't really want that attention either," Millie admitted, wrapping her arms around Y/N's shoulders. "But we'll do that later. I owe you snuggles."
"And now you owe me a round with that ass," Y/N told her as he carried her back out to the couch...