Peel the eggplant and cut into ½-inch dice (about 3cups). Core, seed, and peel the peppers. Cut away any white pith inside the peppers and cut into 1-inch squares.
Fill a pot for the pasta with at least 6quarts water, place over high heat, and bring to a boil.
Peel and thinly slice the garlic. Coarsely chop enough of the marjoram leaves to measure 1teaspoon. Put the garlic and marjoram in a 10-inch skillet with the olive oil. Place over medium-high heat and sauté until the garlic begins to sizzle, 1 to 2 minutes. Add the peppers and sauté for another few minutes. Add the eggplant and season with salt. Lower the heat to medium, cover the pan, and cook until the eggplant is tender, 6 to 8 minutes.
While the eggplant is cooking, peel the tomatoes and coarsely chop. When the eggplant is done, add the tomato, season lightly with salt, and cook, uncovered, until the tomatoes are reduced and the liquid they release is evaporated, 10 to 15 minutes.
Add about 2tablespoons salt to the boiling water, put in the fusilli, and stir well. Cook until al dente.
While the tomatoes are cooking, slice the flesh of the olives away from the pits. When the tomatoes are done, add the olives, cook for 2 more minutes, and remove from the heat.
When the pasta is done, drain it well, toss with the sauce, and serve at once.
You can make the sauce up to 1 day ahead and refrigerate it. Wait to add the olives until you are ready to cook the pasta.