Combine the strawberries, raspberries, cherries, and blackberries with the wine, sugar, and cinnamon stick and simmer over medium heat until the fruit starts disintegrating, 1 to 3 minutes.
Combine the cornstarch with a small amount of water into a slurry with the consistency of heavy cream. Add the slurry to the simmering berries and thicken to a medium to hea