Considering that Nehal is another manifestation of Basim's memories as Loki, is that she was basically a hallucination the whole time, nods to the title of the game: Assassin's creed Mirage. In fact,the brilliant detail in the title not only hints at the djinn, who is referred to as a hallucination in dreams, but that Nehal was a hallucination from the very beginning of when the game begins and is visible even when Basim is awake.
Because the manifestation of Basim's memories as Loki, Nehal, is a girl compared to a male as Loki is depicted. Well, if you consider that Loki is famous for not having a single gender in mythology you can understand why.
If you think logically you will notice the differences between how Odin and Loki approach their hosts. Odin never once tried to hide the fact that he was Odin from Eivor and was always upfront with her, but Eivor simply couldn't understand why she was seeing Odin. Contrasting this, Loki — being the trickster god — decided not to be upfront with his identity, so he became Basim's imaginary friend, taking on the Nehal identity. In wanting Basim to remember his past life, he decided to remain vague and at the at the same time helped him search for the ISU facility where he was being tortured.
