A promise
Our story begins outside the Gryffindor common room where The Fat Lady hangs. Her friend Ernie is talking to her on a Sunday afternoon.
Ernie sighed. "I want to be able to talk to you like there's no one listening."
The Fat Lady asked, "Why would a Hufflepuff student wish to do that for a mere painting?"
Ernie replied, "You're the most beautiful lady I have ever met. The fact that you're a portrait doesn't bother me in the slightest."
The Fat Lady frowned. "I have hung here for many years and I shall hang here for eternity I'm afraid."
Ernie muttered, "No, you shall not. I'm going to move you somewhere where we can have a proper conversation and that's a promise."
The Fat Lady smiled. "Well, I will hold you to your word, Ern. You might want to move aside though to let those poor young Gryffindors in."
Ernie turned around and noticed a group of Gryffindors waiting to get into their common room. He blushed. "I'm sorry, you should have spoken up. This lady here is just so entrancing that I forgot she guarded your common room."
The Gryffindors sniggered and on the way past, one shouted, "You could aim higher, Ernie!"
The Fat Lady swung shut and mumbled, "Those damn Gryffindors are so rude."
Ernie grinned. "I never heard a thing."