A daughter convinced she's a space alien. Callously codependent gay best friends. Families ragged from divorce, disease, and death. The universe in Leavitt's 28 stories would be the envy of any author with ''The Paris Review'' on speed dial. This collection runs from 1982's ''Territory,'' one of the first gay-themed stories published in ''The New Yorker,'' to 2001's ''The Marble Quilt,'' allowing readers to take stock of Leavitt's evolution as a writer and storyteller, to note how he's moved from the familial and lyrically prosaic to rougher, more exotic and playful territories. Leavitt's prose seldom really soars, but it doesn't need to; his stories offer insight into the knotted pacts we make with the world, and with ourselves.