So far in SM Stirling's Emberverse series Vol II, even numbered chapters are about American characters introduced in Vol I and odd numbered chapters are about new British characters descended from (?) or at least linked to characters in a historical fiction diptych by Arthur Conan Doyle. I am finding the Brits more interesting because of their family history and because they are subjects of Charles III in Changed England.
Both groups contain a Tolkien fan and Tolkien's fantasies are suddenly more relevant to real life. When the two groups meet, our British hero's son and our American hero's sister-in-law might find that they have much in common... But I am never good at anticipating an author's intentions.