Hello!
So, I found an assassin's creed roleplay site, www.ontheroofs.boards.net. This site looks pretty cool and I wanted to let you know that something like this exist. On this forum you can choose from three groups: Assassin Brotherhood, Templar Order and common civilians. With your character you can aslo join The Blighters or The Rooks. About places where you can create your post, they are same as in-game (seven boroughts - City of London, Westminster, Southwark, Whitechapel, River Themes, The Strand and Lambeth).