It could be Marcel. He has a long - standing relationship with the Mikaelson family, and his connection with Rebekah could deepen during her pregnancy. He might be the one to support her through the difficult times.
One possible storyline could be Rebekah dealing with the challenges of being pregnant in a world full of supernatural threats. She might have to hide her pregnancy from her enemies to keep herself and the unborn child safe.
I'm not sure specifically which story he tells as there are many moments in 'The Originals' where Klaus interacts with Hope. It could be a story about their family's history, perhaps about the Mikaelson family's past battles or their supernatural origins.
The significance is multi - faceted. Firstly, it shows the relationship between Rebekah and Hope. Rebekah may be using the bedtime story as a form of emotional connection. Secondly, the stories might have cultural or family - related elements that are important for Hope to know as she grows up. It's like a form of heritage - passing in a gentle, bedtime way.
To bond with her. Storytelling is a great way to create a connection between a father and a daughter, especially in their case where there are so many complex family issues and a rich family history.
She could tell a fairy - tale - like story, with princesses and knights. Or perhaps a story about the special powers in their family and how they should be used for good.
Rebekah was significant as she was the one chosen to be Isaac's wife. Her kindness at the well was a sign that she was the right person. Her role was crucial in continuing the family line of Abraham through Isaac.