On the other hand, a GIR may eventually fade into the background, remaining an NPC, and perhaps even losing contact with the main characters. We have in fact started games where everyone was a GIR, and ended up developing the characters into fully fledged PCs within a few sessions. I have also experimented with using a whiteboard as a gaming surface. My thought was that each player would 'own' a whiteboard pen of a particular colour, and could draw or erase anything they like in their own colour. I as GM would have black, so everything I drew was easily distinguishable from everything the players drew.
Most people have a pretty clear idea what makes for a well evolved character.
Unfortunately, most people's ideas are not the same as the people sitting with them at the table. Some people like to focus on the appearance of the character, their habits, and what they have in their pockets. Figure out how the character acts and you get to know who the character is. Figure out who the character is, their motivations, their fears, their anxieties, and you will get to know how the character acts. These are not the only ways to think about what makes a good character.