How do the reasons people post misinformation affect how they respond to fact checking interventions? In this research, we conducted a qualitative study of people who shared misinformation. We started with stories marked as false by a popular fact checker, Snopes, and identified people who posted those stories on Reddit. We interviewed the posters about the story they shared and their five behaviorally distinct personas: Reason to Disagree, Changed Belief, Steadfast Non-Standard Belief, Sharing to Debunk, and Sharing for Humor. Our findings suggest that research to craft better interventions to counter misinformation might benefit from tailoring to specific personas that can serve as design tools for on-going misinformation intervention research.