Rat Patrol 01
Rat Patrol 01 is a team formed to observe the behaviour of the PMC's. Rat Patrols members include:
Snake first meets Rat Patrol in the middle east, where they were the contacts he was told to meet. They tell him at first that they are there to monitor PMC activity.
The team utilises the Sons of the Patriots system, which allows them to "operate as one". This is shown right after Solid Snake and Rat Patrol escape from the Advent Palace, and they are ambushed by several FROGs (one of which shoots Johnathan in the arm - though the pain is supressed due to SOP). The group them simultaneously shoot the FROGs.
At the end of the game, it is revealed that they were sent by the Patriots to help Snake take out Liquid. Drebin shows this by rearranging the letters from "Rat Pt 01" to "Patr10t".