The River Twice by Brenda W Clough

SPSFC

Calla Ang has always known her own power. Her grandmother is the dictator of Jalanesia in Southeast Asia, and Calla's future is to follow in her footsteps. But after the Victorian time traveler Jack Wragsland invites her to 1867 to show Charles Darwin what a real scientific revolution looks like, Calla returns to the 21st century to discover Jalanesia is no longer the country she knew. As she and Jack thread their way deeper into an interlocking maze of alternate realities, there always seems to be a second chance...until suddenly there isn't. The only certainty Jack and Calla have as the universes change is each other. But if she can't learn to handle power wisely, then even love will not be enough to save Calla, Jack, or her country.