Explanation: The Optimates and Populares were the two major political alignments of the Late Roman Republic. The Optimates were the reactionary and conservative supporters of the rich, while the Populares were reformers in favor of the poor and veterans. They were not formal parties, and politicians could (and did) shift between them as the political winds changed. Both sides engaged in copious amounts of corruption, illegal activity, street violence, murder, and general dickheadery, though as a staunch Populare I must point out that the Optimates started it!
As you can see here, there can be cooperation... or there can be confrontation.