|"What the hell are you?"
|"What's the matter? The CIA got you pushing too many pencils?"
The Fire and Stone Engineer was one of the last surviving Engineers stationed on LV-223. He was encountered by Galgo Helder of the Geryon after its fateful expendition to the moon. He was hunted down and later killed by the Predator Ahab, with the help of Galgo.
When the crew of the Geryon first landed on the now lush moon of LV-223, the Engineer kept a watchful eye, observing the Helios vessel from a distance.
The Engineer is later fully encountered by Galgo when he Piper and Higgins were sent to the Perses by captain Angela Foster for reinforcements. The Engineer is seen stacking a pile of dead Xenomorphs, before Galgo quickly escapes from the scene.
Once the crew manage to escape from the Helios and reunite with the rest, the crew retreat into a previously encountered crashed derelict ship, with the Xenos on hot pursuit. Deeper within the interior of the derelict, they encounter a still operational laboratory to create life. Crew member Clara Atkinson wishes to document the chamber and stays behind, the crew unintentionally leaving her. Her lover James Weddel notices this and returns to the chamber to find her. The two are soon cornered by a group of Xenomorphs, as the two prepare for death, the Engineer suddenly emerges within the chamber holding a rifle-like weapon. The Xenomorphs attack him but are quickly incinerated by the superior being's weaponry. After the battle, Clara expresses her gratitude towards the Engineer and thanks him for saving them. The Engineer replies by pointing his gun at them and incinerating them like the Xenomorphs he had just fought. He then crushes Clara's recording device and follows after the retreating Xenos, her footage of all the events on the moon that she had witnessed being destroyed.
Meanwhile, back in the Perses, the Predator Ahab boards the vessel and keeps Galgo hostage. He reveals to him that he is hunting the same Engineer that Galgo had encountered, and forces him to return to LV-223. Once returning to the moon, the two venture into the jungle and come across the same pile of dead Xenomorphs Galgo had previously encountered, although the pile this time was immensely larger than before. Galgo and Ahab eventually find Angela and fellow crewmembers Chris and Jill Hanlock, still on the moon. Foster explains to Galgo that the Engineers having been purging the moon of all wildlife, "clearing up" anything living they come across.
Whilst further exploring the jungle, Galgo and Ahab eventually, rather accidentally, meet the Engineer face to face. Galgo suddenly flees the scene, much to Ahab's surprise and after a brief battle, the Engineer quickly overpowers him, breaking an arm and a leg. Ahab retreats back into the Perses, the Engineer in hot pursuit. Ahab in a last ditch effort, manages to impale a harpoon into the Engineer's chest. The Engineer, however, is able to tear it out and prepares to finish Ahab off. Just before the Engineer kills the weakened Predator, Galgo returns and shoots him in his chest wound with the Engineer rifle that Galgo had previously found. Ahab finishes the job by setting a Self-Destruct Device, escaping the Perses and blowing up the ship. As Galgo reunites with Foster, Chris and Jill, Ahab returns to the wreckage of the ship to collect himself the skull of the dead Engineer, finally obtaining the trophy he desired.