I'm not sure specifically who Barbara Noel is without more context about this 'Barbara Noel story'. It could be an ordinary person with a unique experience, or perhaps someone known within a particular community or family.
Alexis might confront Beckett directly. She could say something like 'I think you're cheating on me. What's going on?' This is a very straightforward approach.
I don't know who Alexis is in this story without reading it. But it's likely that Alexis is either the main character or an important figure in the events that unfold in the 'creepy subway' setting.
A lawyer could be an important character. This lawyer takes on Alexis's case, believing in their innocence. The lawyer has to battle a corrupt legal system or powerful opponents who want to see Alexis locked up for good. The fanfic could show the lawyer's strategies and how they build a case in Alexis's favor.
Perhaps there have been some rumors or whispers in their fictional world that have reached Alexis' ears. Even if they are baseless, they can plant the seed of doubt in Alexis' mind, making her think that Kate is cheating.
She could be defensive of Beckett. Since Alexis probably has a good relationship with Beckett, she may try to convince Castle that he's wrong and that Beckett didn't mean any harm. For example, she might tell Castle about all the positive things Beckett has done for her.
Papa Noel's real story is also intertwined with various cultural beliefs. In some Latin American countries, Papa Noel is a key part of Christmas celebrations. He is seen as a jolly old man who brings joy and gifts. His story has been influenced by different factors like local folklore, religious beliefs, and the general idea of a benevolent figure who spreads happiness during Christmas. For example, in some places, children leave out cookies and milk for him, just like they do for Santa Claus in other parts of the world. This shows how the concept of Papa Noel has been incorporated into the fabric of Christmas traditions in these regions.
The Noel Diary is purely fictional. The author crafted the plot and characters to tell an engaging story rather than drawing from real events. However, it might incorporate elements that feel relatable or common in human experiences to make it more compelling.