Mercenaries were an antagonistic organization featured in Drake's Fortune, and a collection of playable Villain skins in the multiplayer mode of Among Thieves. They are a group of highly trained South American mercenaries that worked under the command of Atoq Navarro, who was hired by Gabriel Roman and served as the main group of antagonists during the second half of Drake's Fortune, during which they also met their demise by Nathan Drake and the descendants.
Roman was aware that Victor Sullivan was close to finding the treasure along with Nate. Roman wanted compensation for money Sullivan owed him and hired Navarro and his mercenaries as muscle. Roman knew Navarro personally, and he served as his lieutenant and right-hand man. Both of them and the mercenaries first appeared in "A Surprising Find", in which several of them perished when the German U-Boat exploded after Sully's apparent death, forcing them to chase Nate as he fled. The mercenaries failed to catch Nate, who had reunited with Elena Fisher, and incurred numerous losses while attempting to stop their escape through the temple ruins in the Amazon rainforest.
They did not reappear until "Sanctuary?", in which they were seen guarding the Spanish monastery, being fought throughout the entire complex. Two were keeping an alive Sully hostage, telling him to stop telling the same stories over and over, and to find out where the treasure was instead. After his rescue, Nate ventured through the monastery on his own, fighting mercenaries from time to time, losing them entirely as he descended into the treasure vault and the bunker.
The mercenaries and their leaders, Roman and Navarro, eventually re-emerged in "Unwelcome Guests", in which Elena was taken hostage. This was also the first time they ran into and engaged in large scale combat with the descendants. The same descendants fought and killed many more mercenaries during "Gold and Bones", forcing Navarro to flee with El Dorado and Elena after he betrayed and killed Roman. In "Showdown", the mercenaries tried to prevent Nate from killing Navarro, but they failed and were killed along with their boss.
Allied with Eddy Raja's pirates, the mercenaries field a more advanced operation, and the two groups did not appear to interact at all. They have primarily occupied the monastery, seemingly using their ship at the coast as a way to resupply and reinforce. The monastery seems nearly unreachable using driven vehicles, and unlike the pirates, the mercenaries were never seen using any except a single helicopter. Said helicopter was seen by Nate in "Trapped" and recorded by Elena as well. It was used to transport Roman, Navarro, and Sullivan to the monastery from the Drowned City, as well as airlift El Dorado to the ship, where it crashed due to one of the mercenaries, Dillon, accidentally shooting the pilot, Javier.
Their military outfit predominantly consisted of dark-colored clothing, mainly cargo pants, body armor, bandoleers, and extra pouches on their person. In "A Surprising Find", they only used the AK-47 and the PM - 9mm, which they soon replaced with more advanced weapons, such as the 92FS - 9mm pistol, the M4 assault rifle, and the SAS - 12 shotgun. They did still use the same Mk-NDI grenades and M79 grenade launcher, but unlike the pirates' Wes - 44, they used Desert - 5s with an added laser sight, with which they frequently took on a sniper role. They were otherwise not seen using turrets, unlike the pirates.
Several of the mercenaries appear in Among Thieves as multiplayer skins. Dutch and Blaine are unlocked at levels seventy and eighty, respectively. Javier is unlocked after the purchase of the Drake's Fortune Multiplayer Pack, and is also available in Drake's Fortune as the villain skin named 'Mercenary'. Dillon is available through the Sidekick Skin Pack.
Blaine and Dillon are, in fact, generic mercenary enemy models, with the latter prominently appearing in the "Helicopter Ride" cutscene, where he is kicked out of the vehicle by Elena. During his fall, he shoots the pilot, who actually appears as Javier. Dutch is also a generic model and serves as the mercenary using the M79 grenade launcher.