Characters involved: OC or very minor canon character (such as Lisa Turpin) , perhaps a couple of proffessors
Mood of plot bunny: I'm not sure
Plot line: OC is muggle-born and has a squib parent. The parent has told them all about the wizarding world. The main character is eleven and has what he/she thinks is a great life. Then he/she gets a Hogwarts letter and decides not to go because he/she doesn't want to leave the life he/she has right now, and because he/she is not impressed with the way the wizarding world treated his/her squib parent. The squib parent thinks he/she should go. Hogwarts/the Ministry is not happy.
Other details: This would probably be a multi-chapter story, I think, but if you think you can do it in a one-shot, go ahead!