Final answer:
In the novel 'Illuminae,' Kady Grant's username is 'ByteMe', which reflects her computer skills and sassy character.
Step-by-step explanation:
In the book Illuminae, the main character Kady Grant's username is ByteMe. Throughout the novel, readers see Kady displaying her prowess in hacking and computer skills using this moniker.
Her username is fitting considering her sharp wit and skills in information technology, both of which are central to the plot and to her character's actions as she navigates through the chaotic circumstances aboard the space fleet.