Currently the game will take a look at the ID of the tile that you're standing on and then match that with the appropriate entry in the "profilePictureArr" array. This means there are as many entries in that array as there are tile types. Most of those entries are 2 as the normal face is the most common.
The system is a little bit more rigid than I'd like it to be, meaning if I want to add more profile pictures for new character types, the ID that gets passed into the update profile picture function will be offset by a value associated with the character ID. For example, if they're using the cat avatar, the offset will be ID + 12 (assuming there are 12 different faces per character).
I've also setup the first frame of this profile movieclip to essentially store all the miscellaneous, non-specific, profile pictures such as NPC image or an image of a wall. A second array called "miscPictureArr" stores all the frame numbers for the miscellaneous pictures that need to be shown.