The writers found that Niko needed a motivation to come to America, so they created his cousin, Roman. Dan Houser felt that the two could not be brothers as there would be a deeper level of familiarity than necessary. He described the two as a double act, with Roman's fantasist charm playing off Niko's tough cynicism. The team gave other non-playable characters (NPCs) more definable behaviours and dialogue to make them feel more alive. The writers initially considered having a smaller group of characters, but found that the story became boring and that players were less likely to explore the world. The stranger characters found in the game world were based on the "crazy people" that populate New York, according to Dan Houser, which in previous games were only able to be captured through radio stations or mild pedestrian behaviours. The team based the ethnicities, clothing, and behaviours of the NPCs on the photographs and videos that they captured around New York, divided into different areas; they created mood boards for each location. The NPCs also converse in different languages.