 The concept of a computer AI guiding the player through experimental facilities to test the portal gun was arrived at early in the writing process.They drafted early lines for the yet-named "polite" AI with humorous situations, such as requesting the player's character to "assume the party escort submission position", and found this style of approach to be well-suited to the game they wanted to create, ultimately leading to the creation of the GLaDOS character.GLaDOS was central to the plot, as Wolpaw notes "We designed the game to have a very clear beginning, middle, and end, and we wanted GLaDOS to go through a personality shift at each of these points."