http://allrecipes.com/recipe/blueberry-and-raspberry-pancake-topping/

1/2 cups frozen raspberries
1 cup frozen blueberries
1/2 cup white sugar
1/4 cup water

Combine the raspberries, blueberries, sugar, and water in a small saucepan;
bring to a boil and cook at a boil for 5 minutes, scraping the bottom as needed to keep from burning.
Reduce heat to low; simmer the mixture until thick, about 10 minutes. Serve warm.