Quarter the tortillas, then use a paring knife to trim each quarter to the shape of an arch with a pointed top. Using the paring knife or kitchen shears, cut out the jagged shape of a shark's mouth, about 1 1/4 inches wide and 3/4 inch tall, in the bottom third of the arch in 4 of the tortilla pieces. These will be the top tortillas.
Assemble the quesadillas: Divide the cheese among the 4 bottom tortillas. Place a strip of roasted red pepper across the bottom third of each bottom tortilla and arrange a top tortilla over it, making sure the red shows through the cut-out mouths.
Melt the butter in a large nonstick skillet over medium-high heat. Arrange the 4 shark quesadillas in the skillet. Cook until golden brown and crisp, about 3 minutes per side. Transfer to a serving plate. Dip the black olive slices in the sour cream and place 2 on each shark quesadilla for the eyes, using the sour cream to make them adhere.