Yaaxil

The Yaaxil are Paititian "protector goddesses" who were dedicated to guarding the Silver Box of Ix Chel, which was stored within a cenote on the outskirts of Paititi itself. They are led by the Crimson Fire.

History
Even most Paititians don't know that the Yaaxil are real, though one believed that they are and wrote about them.

Lara Croft saw some creature killing a Trinity soldier near Kuwaq Yaku. She described it to Abby as fast and making hissing sounds, Abby thought Lara was joking, as she described the legend of Pishtaco, a mythological boogeyman figure in the Andes region of South America. Lara was however certain on what she saw.

Lara again encountered the Yaaxil when she went into cenote, to retrieve the Silver Box. The Yaaxil tried to stop her reaching the box, but once Lara entered the Box's room, the Yaaxil stopped, and only after they realized that the box isn't there they attacked Lara again. The Yaaxil chased Lara through out the cenote, until she took a long jump off of a cliff and climbed out.

Yaaxil had also tunneled towards the Mission of San Juan and there had been sightings of them there. Some were near the Ancient Aqueduct tomb, but most were around the tomb known as Tree of Life.

The Yaaxil still protected the City of the Serpent, as is was where the ritual of the Silver Box of Ix Chel took place. Crimson Fire who represented Chak Chel waited for her counterpart Ix Chel, to complete the ritual. Lara once again came and took the place of Ix Chel, and made a bargain with the Yaaxil to stop Pedro Dominguez who wanted to remake the world instead of restarting the sun. The Yaaxil killed every Trinity soldier they saw, amongst them the Trinity High Council, effectively dismantling the Trinity organization.

It is unknown what happened to the Yaaxil after Crimson Fire completed the ritual, as Lara took the Silver Box and the Key of Chak Chel with her when she left. But it is likely that they continue living in peace now.