When I first started thinking about this challenge, Dobby immediately came to mind. Here is the fruits of my labor...

Dobby is afflicted by his master,
Day-in, day-out unhappiness abounds,
Yells and curses fill the house with loud sounds,
Punishments leave small holes in the plaster.
Secrets build, which lead to disaster;
Harry’s story fascinates, astounds;
The master’s scheme to his conscience confounds,
Everyday the plans move even faster.
Determination now fills up his heart,
Harry needs to stay away from school;
His mail will not reach him, do his friends forget?
The wizarding world and Harry must part;
If he goes back the results will be too cruel,
Dobby will keep Harry safe from the threat.