Derpy "Muffins" Hooves has always had vision trouble. Her crossed eyes are troublesome enough, but she's had visions since she's been a foal.
They're not too bad. She can't identify ponies on sight alone, and finding specific objects is hard, but despite how strange things look, she gets by. She's tough, after all.
This time, a strange pony has appeared during her visions, and she's not sure what he wants. He asks about strange things, and he's real mean. Derpy can handle it, right?