THE COLOR PURPLE is an interesting case: The lead (Celie) only has one solo ("I'm Here"), which comes at the very end of an almost three-hour musical, and one tiny little song ("Somebody Gonna Love You") at the beginning. She sings a lot in ensemble numbers and has a lot of stage time, but as compared to other leading roles (just for example: Momma Rose), she doesn't exactly have the amount of solo music you'd associate with a lead.
"You travel alone because other people are only there to remind you how much that hook hurts that we all bit down on. Wait for that one day we can bite free and get back out there in space where we belong, sail back over water, over skies, into space, the hook finally out of our mouths and we wander back out there in space spawning to other planets never to return hurrah to earth and we'll look back and can't even see these lives here anymore. Only the taste of blood to remind us we ever existed. The earth is small. We're gone. We're dead. We're safe."
-John Guare, Landscape of the Body