In a cocktail shaker, add the blueberries and simple syrup. Muddle until the blueberries release their juices.
Add the lemon juice, vodka, and ice to the shaker. Shake until well chilled.
Set out two lowball glasses. Fill each glass with ice and strain the blueberry mixture over the ice, filling each glass about three-quarters full.
Top each glass with club soda. Garnish with lemon slices and fresh blueberries. Enjoy!