Rick buried a machete in the inmate's skull, ending his little rebellion before it could take off. In response, Tomas' buddy Andrew bolted, only to find himself outside in the midst of a group of walkers, where he was locked out and left to die by Rick.
Unfortunately, Rick's failure to see Andrew's death through came back around, as he survived, lured walkers into the prison, and stirred up the chaos that led to T-Dog and Lori's deaths, his actions tainting the group's new safe haven and forever changing the group - especially Rick - going forward.
Dawn herself was frequently hard to get a read on, slapping the kidnapped Beth one minute and trying to be genuine with her another, though her desperate obsession with maintaining her power in the face of dissent led to her attempting to manipulate Beth to take her side.
When Rick and the gang showed up to trade her people back for the release of Beth and Carol, her arrogance brought about her own downfall, as she shot Beth instinctively after being stabbed before Daryl put her down in return. She only appeared in a handful of episodes, but her final action undeniably robbed the group of much-needed hope at a time when they needed it most.