<p>With the popularity of the gaming industry, game streaming appeared and became a global phenomenon with high participation in recent years. Game streaming platforms such as Twitch had millions of active users participated in the community by watching and chatting. Yet there was lack of investigation about how chat behaviors connected with the overall participation in game streaming community. This study aims to describe and analyze the roles taken on by viewers as they engaged in chat while watching game streaming and identify how these roles influenced participation. I designed a qualitative study with online observations on several Twitch channels streaming Overwatch. By analyzing the chatlogs collected, I identified four social roles among chatters: Lurker, Troll, Collaborator, and Moderator. A discourse analysis was applied to further investigate the interactions among these roles and how they shape the conversation in chatrooms. With these findings, I generated a four-role model that specific for chatters in Twitch personal channels. Limitations of this study and suggestions for future research were also provided.</p>