You must fill out an application for Features, and it's strongly recommended you log into the game to read the 'news' and talk to the players of characters with strong ties to that Feature. But if you'd like to just take a quick look at the application, it's available at http://www.alereflammas.com/ under Applications.
For Extras, which are characters from the books with less 'air-time' than other characters, you can create the character directly on the game and go through the on-game approval process that all new characters do.
Here is a non-comprehensive list of our currently open Features. For a fuller list, log into the game at alereflammas.com 9034 and see '+help features' for the commands to search our feature database.
Arthur, Molly, Bill, Charlie, Percy Weasley
Filius Flitwick, Xiomara Hooch, Binns, Pince, Eugenia Sprout
Hannah Abbott, Colin Creevey
Katie Bell, Angelina Johnson, Alicia Spinnet, Oliver Wood
Lavender Brown, Millicent Bulstrode, Padma and Parvati Patil
Seamus Finnigan, Neville Longbottom
Cho Chang, Luna Lovegood
Fleur Delacoeur Weasley, Pansy Parkinson Malfoy
Dobby, Argus Filch, Peeves, Winky
Bloody Baron, Nearly Headless Nick, The Grey Lady, The Fat Friar
Rita Skeeter, Nymphadora Tonks
... and more!
Malcolm Baddock, Susan Bones, Terry Boot
Gabrielle Delacoeur, Dennis Creevey
Sir Cadogan, The Fat Lady
.... and many, many more!
Don't hesitate to log into the game and ask questions.