I thought of this really cute idea where you find a goblin outside the walls of the kingdom gnawing on some grass, and take him/her in to care for, and feed them. You can dress them up anyway you like, choose what personality they have, and what shape they will become when they become chonky.
The story: You (knight) are on your regular patrol, when you find a thin, almost bone thin goblin munching on grass. The goblin tells you they’re a hungry gobbo, so you take them, and feed them.
I also thought of some cute/goofy things the goblin can do.
Each object in each scene can be grabbed, and carried by the goblin. The goblin might get bored if you don’t pay attention, and begin messing with the furniture in your house. Gobbo might do silly things with the furniture. If your goblin likes you, they’ll likely go up, and snuggle you. An adult goblin grows up to about 2 feet tall. They do get taller, but those are called great goblins.
Fat goblins get gassy, so they might burp, or fart a lot once they become fat. This will be another thing you can set.