“On Venlafaxine and Ghosts” offers an unflinchingly realistic yet humanizing portrayal of mental illness. The casual, humorous tone pulls us in before delving into familial memories that are as dark as they are contradictory — depending on who recounts the memory. Whatever one’s brain chemistry, nobody wants to think about how personal memories are fallible or that they might be the villain in their own story. There are no easy antagonists in Reid Kerr-Keller’s work; he skillfully crafts complex characters that are heroes of their own worlds.