While he was eager to get big and round and fat, Peter knew that he had to take things slowly. He was testing out the effects of this supposedly magic potion after all, he reminded himself, his hand still to his stomach; fingers shaking slightly with nerves. He forced himself to keep his eyes open as he made his wish, looking down at himself expectantly.
'I wish I gained twenty pounds.' The moment the wish formed in his mind, Peter felt his stomach billowing out against his fingers. He looked down as the flesh rose slowly, warm and soft, until he had a rounded stomach on him that just stuck out over the waistband of his school trousers, which had become a little tight. Peter gasped as he moved his hand away, looking down in amazement at the stomach he now had on him. He bought his eyes slowly up to meet the witch's, she just smiled in response, her eyes notably focusing on his added girth.
"It suits you," she remarked with satisfaction, "Remember that everyone will have always seen you this size," she added, before giving a cackling, lilting laugh, "They'll always seen you as a bit chubby. They'll put that gut of yours down to food, not anything else." Peter felt over his newly added pounds with some amazement, a tingle going through him at that. The idea of having always been seen as being on the chunkier side appealed to him more than he would ever care to admit.
"Thank you," Peter bowed his head to the witch, "I mean it. This.. means a lot to me." She just focused that same smile on him, holding up her hand in a gesture for him to leave.
"Go. Explore the effects of this new gift of yours." Peter turned and left the shop, the door closing behind him with a light thud. He turned automatically, only to stare with wide eyes at the blank expanse of wall where the shop had been. He frowned, before touching his hand to his stomach, the pounds were still there. He had definitely been in there, Peter realised as he poked at the added fat to his lean frame, but there was no sign of the shop before his eyes. Forcing it to the back of his mind, Peter began walking home, his thoughts filling of what he could do with his new gift.