In Dark Fire Alexa has a big role. Zanna noticed the first sign, Alexa had wings growing out of her back. David tried to tell her that Alexa was an angel sent by the fain to be a beacon of hope in the new beginning. Instead Zanna turned him back and refused to accept it.
Later on in the book Zanna notices more. When she was talking to Alexa, Alexa said she remembered something from long ago. David's theory was that she picked her parents. She was a fain that wanted an experience as a human girl and she chose Zanna and David to be her parents.
At the end of the book Alexa joins with G'Oreal and some other dragons. They join David, Lucy, Bella, Tam Farrel, Bella and Gwendolen (Figure) (Lucy's IT dragon) when the ground opens and the fire eternal comes through and they all are wisped away to another world.
In Fire World she is not mentioned until the end of the book, they call her Angel. Angel/Alexa was first spotted by Penny (Lucy) and not mentioned until the librarium transforms into an ark. She asks David to read her Snigger and the Nutbeast writen by David Rain. She goes away for a few chapters, When Harlan/Arthur is telling David how Abbot Hugo dies Angel comes back and tells them that Hugo is happy. Harlans eye heals. She is the only one (besides Gadzooks) that knows that they have another life back on Earth.
In the Fire Ascending her role is very important. Agwain falls of a mountain and is rescued by firebirds telling him he is chosen for illumantaion. He is shown millions of fire stars and he choses Alexa. Alexa still appears to be speaking to him and he can speak to her suggesting that he is sharing a body with her. He/she defeats Voss in the end and time is reset. She/He is now an actor and called Angel, This is her/his last appericence int the series.