Preheat grill to medium-high heat.
In a large bowl, whisk together olive oil, lemon juice, garlic, oregano, thyme, salt, and pepper.
Marinate fish in half the mixture for 10 minutes.
Toss vegetables with remaining marinade.
Grill vegetables for 8-10 minutes, turning once, until tender and lightly charred.
Grill fish for 4-5 minutes per side until it flakes easily.
Arrange fish and vegetables on serving platter.
Top with olives, capers, and fresh basil.