Characters that follow the player throughout a games are called companions. Companions are commonly part of the story in narrative focused games, such as role-playing games, but are also present in games with a focus on gameplay. This report investigates companions through a review of the current literature and an analysis of games that use companions. The analysis revealed several shared tendencies between the games and these tendencies were used to construct a model of non-player character companions. Using the model, the effect of companions on player choices was investigated using a game with two identical versions of the game, but with different companion types categorised by the model. The companion with higher narrative purpose was able to affect the player’s choice significantly more than the companion with less narrative purpose. Additionally, the test participants were able to an extent, categorise the companion accordingly to a hypothesised model, indicating that the model can be used to categorise companions.