Preheat oven to 425°F.
Cut parchment paper into 4 rectangles, 12 x 18-inches each; fold each in half crosswise to crease, then reopen.
Put the tomatoes and olives in a medium bowl. Spoon the tomato mixture onto one-half of the rectangle as close to the center as you can. Top each with 2 chicken thighs. Drizzle with 1 tablespoon olive oil, sprinkle with salt and pepper, a top with a sprig of thyme.
Tightly roll each side of the open edges, pressing down to form a tight seal so the moisture can't escape.
Put the packages on a rimmed baking sheet and put in the oven. Bake until the chicken is cooked through and the tomatoes are tender and saucy, 25 to 30 minutes (open up 1 package to check).
While the chicken is cooking, combine the quinoa and water in a medium pot and bring to a boil. Reduce heat, cover, and simmer until the liquid is absorbed, about 15 minutes. Let stand 5 minutes, then fluff with a fork and season to taste.
When the packages are ready, carefully open each. Serve hot or warm right in the packages or on plates with the juices poured over. Serve with the quinoa.