Live streaming has spawned a new business model called live-streaming commerce (LSC). Interactive LSC features affect viewer purchasing behavior. This study empirically examines two types of social interactions in danmaku: transaction-oriented and relationship-oriented. Viewers in the first category focus on products and transactions and tend to talk non-emotionally. While relationship-oriented viewers might treat broadcasters as friends, using emotional language in their interactions. Our econometric model shows a curvilinear association of relationship-oriented social interaction and viewer purchase behaviors in LSC, but social interactions have varying effects on viewer purchase behaviors.We discuss implications of heterogeneous social-interaction strategies across different broadcasters.