Each character starts out with 10 points.
You + 1 point to the character you like and -1 point to the character you don't like.
When a character reaches 0 you eliminate him/her from the list.
The list of characters is long (40!!!) but I had problems to cut it on 40 from 70 characters from "closer selection".
Characters are based on numbers of books they appeared, importance of their role and possibility of forming an opinion about them.



Katie Bell 10
Regulus Arcturus Black 10
Lavender Brown 10
Alecto Carrow 10
Amycus Carrow 10
Cho Chang 10
Vincent Crabbe 10
Colin Creevey 10
Barty Crouch, Sr. 10
Barty Crouch, Jr. 10
Nearly Headless Nick 10
Fleur Delacour 10
Cedric Diggory 10
Aberforth Dumbledore 10
Dudley Dursley 10
Marge Dursley 10
Arabella Doreen Figg 10
Argus Filch 10
Seamus Finnigan 10
Filius Flitwick 10
Cornelius Oswald Fudge 10
Marvolo Gaunt 10
Merope Gaunt 10
Gregory Goyle 10
Fenrir Greyback 10
Gellert Grindelwald 10
Angelina Johnson 10
Lee Jordan 10
Gilderoy Lockhart 10
Xenophilius Lovegood 10
Lucius Malfoy 10
Narcissa Malfoy 10
Olympe Maxime 10
Alastor "Mad-Eye" Moody 10
Pansy Parkinson 10
Quirinus Quirrell 10
Rita Skeeter 10
Horace Slughorn 10
Dean Thomas 10
Oliver Wood 10