Add the cherries, sugar, peppercorns and 1 cup water to a small saucepan. Bring to a boil, then allow that to cook until syrupy and glazed, 10 to 15 minutes. Let come to room temperature. Store any leftovers in the refrigerator for up to 2 weeks.
Combine some ice, the gin, lemon juice, a couple dashes of bitters and 2 ounces of the cherry-pepper syrup in a large cocktail shaker. Shake vigorously and pour over ice-filled Tom Collins glasses. Top each glass with some club soda. Garnish with the cherries and a crack of black pepper.