What the font?

Definitely customized. You know this when 2 letters aren't similar

I think that might be a font because if two letters aren't the same/similar it can also be because one of the letters is upper-case and the other one might be lower-case. :]

http://www.dafont.com/forum/read/53203/what-is-this-font

"Not a font. Pottermore logo was made by TH_NK for Pottermore

http://www.think.eu/our-clients/