How The Player moves Niko is not explicitly stated at any point, however, it is inferred that The Player is physically controlling Niko's body made manifest through the Arrow Keys. Prophetbot remarks that The Player has been guiding them throughout the entirety of their journey despite Niko not contacting them until slightly later from when they woke up, which was the moment The Player began controlling them.
The Player converses often with Niko about their journey and both of their pasts. The Player has the choice of choosing conversational options that will develop their character, for example, Niko will ask The Player if they reside in a city or somewhere else.
The Player's advice is integral to Niko's progress, as puzzles and elements tend to appear outside of the game itself, for which The Player must use these elements to decode various puzzles that Niko encounters throughout their journey.
The Player champions themselves as a 'kind God', which Niko later reflects. The Player is kind and helpful to Niko, returned mutually by the latter. The Player and Niko are implied to have been very good friends from the time they spent together, with The Player having the optional ability to urge Niko to perform actions such as making them do a robot voice and riding around on an automated floor vacuum.
Based on in-game dialogue and options, The Player is equally as determined as Niko to save the world. They often lend Niko their aid in puzzle solving and deciding what action to take next, acting as an adviser or strategist to Niko.
The Player has proven themselves to be very cunning and resourceful, as they are able to improvise solutions and plan for the future on-the-fly. As it is implied that The Player is solely managing Niko's inventory, The Player is able to combine and repurpose countless objects to suit the cause, speeding Niko's progress through the world insurmountably.
The Player is known to easily collapse under guilt, as they're completely unable to hide the truth about The Sun from Niko, even if the user deliberately chooses the "keep quiet" options. The World Machine even taunts The Player for their immense care for Niko by saying "You might as well tell Niko the truth. You do care about Niko, don't you?"
Throughout most of the game, The Player is kept in the dark to the events going on around them, leading them to be outwardly confused, even admitting this to Niko after telling them the truth about The Sun by telling them that they don't know what will happen to Niko.