Liking the amount of content your churning out. Good on ya. So anyway my idea is Lyra x human anon and they're using a belly growth spell on herself, along with some belly play like rubbing, kissing that gets dirtier the bigger she gets. As to how big she gets? Go nuts man :)

Anon smiled to himself as he worked his fingers into Lyra’s gut. The mare’s supple belly was like dough in his hands, and he took great pleasure in feeling her chub squishing in his grasp.

“You’ve really let yourself go, Lyra,” he said. He shot her a grin. “What happened to that thin little filly I met last month?”

Lyra’s answering grin glimmered with mischief. “She learned to enjoy the value of a good meal.” She burped, not loudly, but not quietly, and covered her mouth with a hoof. “Of lots of good meals.”

“Well,” Anon said, “I can’t say I have a problem with that.” He gave Lyra’s belly a good squeeze. Without even thinking about it, he bent over and, pursing his lips, gave her a wet raspberry right at the top of her rippling tummy.

He savored the sound of Lyra’s sharp intake of breath, savored the warmth of Lyra’s soft belly against his face. He nuzzled her belly for a few moments more, still kneading it, still grabbing small handfuls of her gut -

- and slowly, ever so slowly, realized that the handfuls of flesh he’d been grabbing were beginning to spill out from his grip. He opened his eyes and gaped. Lyra’s belly was at least half again as large as it had been when he’d started.

He glanced up. Lyra’s horn was shimmering green. There was a shy, but knowing smile on her muzzle. “I heard you liked big mares,” she said slyly. “So I thought I’d make sure to get a belly up on the competition.”

“It’s the most beautiful belly I’ve ever seen.” And it was. Lyra had been merely tubby when they began, but by now, with her belly spilling over her waist and the beginnings of a double chin forming over her neck, she was well on her way to being truly fat. Anon leaned in and gave Lyra a kiss. He loved the feel of her soft lips against his, loved wondering how they’d taste after he’d stuffed a cake or two between them -

He moved his attention back to her belly. Kissing it, he found that it was still growing bigger. He made sure to pucker his lips up a little wider and kissed again. The soft belly flesh depressed under the weight of his lips, rippling, teasing as he kissed and kissed her tummy. Lyra giggled as his lips smacked against and sucked on her rolls of fat, which of course only made her double chin shake and jiggle from the vibrations.

“It can be more beautiful,” she murmured. She ran a hoof through his hair and pressed his head lightly against her burgeoning gut. She groaned softly as his face sank into the warm flesh - or, rather, as her stomach grew up around him.

Anon moved to her belly button, a newly massive hole as deep and as wide as his thumb. He lashed at it with his tongue, lapping and licking at it madly. His hands, meanwhile, were free to squeeze and squish Lyra’s bountiful love handles. Admittedly, they were now less handles than enormous, fat-filled eclairs, which rolled and squished against his palms as he ground his tongue even deeper into her belly.

Finally, with a belly that must have weighed at least as much as she did when she started, Lyra let the spell go. She smiled as Anon pulled his face away from her belly and instead pulled himself up onto it. Her belly squished beneath his weight, but held it. The couple met at the bottom of the mountainous gut with a kiss.

Lyra suddenly smiled devilishly. “What’s what I feel pressing into my belly, hm?”

Anon grinned. “Care to find out?”