|This article is about the rodent species. You may be looking for Rat Patrol Team 01, a CID investigation unit deployed in 2014.|
Rats are rodents that typically inhabit sewers and other unkempt areas. They had a negative reputation, with the name of the species when used against a person often being meant to indicate that the person in question has a highly untrustworthy nature. In addition, largely due to their negative reputation as a pest, the term is often used for any vermin of rodent origin that acts as a pest even if they technically are completely separate from actual rats.
During the time of Operation Snake Eater, in August 1964, rats inhabited the Soviet region of Tselinoyarsk. They were the descendents of Norwegian wild rats that were domesticated by humans as pets and lab animals. They also lived within the sewers leading away from Groznyj Grad.
During the Shadow Moses Incident in 2005, various ventilation shaft covers in the tank hangar were left open in order to spray for rats, allowing Solid Snake to crawl inside and infiltrate the cell block. Previously, a group of Alaskan field mice, while not technically rats, had inadvertently shown Snake the way into the hangar proper, with Snake referring to them as "old friends" after returning to the facility nine years later, much to Otacon's confusion.
Behind the scenes
In Metal Gear Solid (and its remake, The Twin Snakes), the player can shoot the rats near the Comm Towers and in the Blast Furnace. Doing this will prompt different responses from Snake's contacts. Also, if the player does not submit to Revolver Ocelot's torture in both games, Snake will have to kill a rat that ingests the PAL key, after he drops it into the drainage ditch of the Underground Maintenance Hangar.
In the non-canon Game Boy Color game Metal Gear: Ghost Babel, while traversing the sewer system of Galuade, there were rats crawling along the floor, with the implication that they were trying to get away from the then-upcoming squall's floodwaters.
In Metal Gear Solid 3: Snake Eater and its various versions (including Snake Eater 3D), the player can capture and/or kill rats in various urban areas as food to consume to regain a moderate amount of stamina. They are also noted by Snake as being fairly tasty.
Dummied dialogue in Metal Gear Solid 4: Guns of the Patriots indicated that, besides their presence in Shadow Moses during Twin Suns, rats would also have appeared in the cut sewer sequence for Third Sun, and would have acted as an aid regarding telling where Gekko were laying in wait to ambush Snake.