Bring 1/2 cup water, the sugar, and fennel and coriander seeds to a simmer in a small saucepan over high heat. Reduce the heat to medium low; cook until the sugar dissolves, about 5 minutes. Let cool, then transfer to an airtight container and refrigerate overnight.
A few hours before serving, strain the syrup into a pitcher. Add the cranberry juice, brandy and pears. Refrigerate until ready to serve.
Add the sparkling cider to the pitcher and stir. Serve over ice.
Photograph by Con Poulos