Ask me for any character I write or have written (OCs included) and I will tell you, if they existed in the Harry Potter universe:
1. Sorting Hat: what house would they be sorted into?
2. Expecto Patronum: what form would their patronus take?
3. Riddikulus: what form would their boggart (read: their deepest fear/the thing they find scariest) take?
4. Amortentia: the three smells they find most attractive/appealing.
5. The Mirror of Erised: what would it show of their heart's desires when they looked in it?
In the past I have done: Anna Murphy, Harry Dresden, Hrothbert of Bainbridge, Sherlock Holmes, Mycroft Holmes, John Watson, Molly Hooper, Greg Lestrade, and Sarah Sawyer.
These are pretty quick to do, so feel free to ask for more than one character. AUs welcome as always.