In the real world, the Rattlesnake Mercenary Group is an international mercenary force for hire, they specialize in spying, gathering intelligence, assassination contracts, and other special operation missions. The organization is lead by Black Mamba. Everyone in this group is named after a snake of some sort. However, only the core members are allowed to name themselves after poisonous snakes like Viper and Cobra.
In Earth Online, the Rattlesnake Mercenary Group was said to be lying "unusually low profile" as stated by Xie Siyun, the vice-leader of the War-Rose Mercenary Guild. In fact, they were so low profile that she didn't even know what they specialized in.
Upon being discovered by Ouyang Shuo, Black Mamba was particularly curious as to how he found out who they were and in the future, the two parties cooperated in order to train members of the Shanhai Military in the ways of Modern Special Operations.