It was a peaceful Saturday afternoon when Mirio decided to spoil Lily with something small—a glittery bath bomb he'd picked up from a magical novelty store downtown. The label said "Mystic Melon Fizz: Soothes the core and calms the soul!" with tiny runes etched around the cap in a soft shimmer. He figured it'd be fun, maybe relaxing for her after a long week of bouncing all over the apartment and melting into his laundry pile again. He hadn't noticed the handwritten fine print on the bottom: Warning: May alter personality temporarily. Effects last 24 hours. Do not combine with other emotional triggers.
He dropped the bath bomb into the tub while Lily excitedly watched, already half-melted against the edge of the porcelain. The bomb hissed with pink foam and released a glittery cloud of melon-scented steam. Lily squealed with joy. "Fizzyyyy~!" She slipped into the tub, her core glowing a soft green under the bubbles as she dissolved slightly into the water. Mirio sat beside the tub, drying his hands with a towel. "Feeling good?"
She blinked up at him once. Then again. Her glow dimmed. Her tentacle-hair stiffened slightly. She puffed up her cheeks and crossed her arms under her chest. "I-It's not like I needed this stupid thing or anything, y-you dummy!"
Mirio paused. "What."
"I mean, I could relax without your help, okay!? Just because you brought me a glitter ball doesn't make you special!"
"…Lily?"
She splashed angrily and looked away, her face a brilliant pink beneath her translucent skin. "D-Don't look at me like that, idiot!"
He stared in stunned silence. Lily, his affectionate, clingy, always-snuggling slime wife… had just turned into a full-blown tsundere. And she wasn't even being ironic.
Ten minutes later, she stormed into the living room in a steamy trail of leftover bathwater, wrapped in a towel she barely even needed. Her body was firmer than usual, her slime held rigid out of sheer flustered energy. Her thighs jiggled with authority. Her chest wobbled with aggressive tsun. "I made you tea. Not because I like you or anything!" she snapped, slamming a cup on the table. "I just didn't want you to die of thirst while being useless!"
Mirio took the cup cautiously. "Thanks… I think."
She sat on the couch beside him, arms crossed, legs spread awkwardly like she was trying to assert dominance but didn't know how chairs worked. "Why are you so close?! Back off!"
"I'm on the opposite cushion."
"W-Well, maybe you should be farther! Or closer! I mean—not that I care!"
He looked at her. "Did something happen in the bath?"
"N-NO! NOTHING HAPPENED! I'M FINE!" she screamed, puffing up with a visible pulse of steam.
"…Was it the bath bomb?"
"SHUT UP!"
The rest of the day was a whirlwind.
At lunch, she made him a sandwich, then threw it at his chest. "Don't complain. I measured the bread thickness perfectly, okay!? I'm not dumb!"
He blinked. "It's great, thank you."
"I-It's not like I made it because I care or anything! I just didn't want your blood sugar to drop and have you pass out like a pathetic human!"
"…You cut the crusts into heart shapes."
She screamed into a pillow and refused to speak for ten minutes.
Later that evening, he tried to watch a movie. Lily snuggled against him without permission, her goo forming into a custom-shaped couch blanket. "Sh-Shut up! You're cold, okay? It's not because I wanted to touch you or anything!" She wrapped her arms around his torso and moaned under her breath. "Y-You better not enjoy this."
"I'm not gonna survive this day, am I?"
The worst part came at bedtime.
Mirio had just pulled on his pajamas when Lily slithered across the bedroom floor with a violently blushing face. Her body was already shifting—breasts bigger, hips heavier, goo visibly warmer. "I-It's not like I wanna do anything lewd!" she shouted, flinging herself at him and landing face-first in his lap. "I'm just helping you relax! Because you'd die without me! Probably!"
Her face rubbed into his stomach, then down toward his waist.
He yelped. "LILY!"
She recoiled with a gasp. "I-I wasn't doing anything! Idiot! Pervert!"
"You just faceplanted into my—"
"STOP THINKING ABOUT IT!"
She rolled under the blanket and cocooned herself around his legs like an embarrassed snake.
Mirio stared at the ceiling.
"…So this lasts until morning?"
"D-Don't get used to it!"
At 3 AM, she rolled on top of him in her sleep and moaned, "Hubbyyyy~"
He blinked. "Wait. That's her normal voice."
She stirred, slowly re-melting into her usual bubbly softness. Her blush faded. Her tentacles wiggled lazily. "Mmnn… my tummy still fizzy…"
Mirio hugged her tight. "Lily?"
She blinked, looking up at him. Then grinned. "Hi, hubby~!"
He exhaled. "Welcome back."
She tilted her head. "Did something happen?"
He stared at her. "You called me a useless pervert and threw a sandwich at me."
She gasped. "Did I cut the crusts at least?!"
"…Yeah."
She snuggled deeper against his chest. "Then it still counts as love."
He shook his head, kissed her forehead, and whispered, "You're never getting another bath bomb again."
"Can I get a cursed shampoo instead?"
"Absolutely not."
And just like that, the tsundere terror of the day ended—leaving only a steamy pillow, a half-eaten sandwich, and a very confused Mirio in its wake.