Xalanyn

"If Halo cannot end them, it must imprison them."

- Grand Edict to 117649 Despondent Pyre

The Xalanyn, also known as the Endless, was an advanced race, whose members were imprisoned by the Forerunners on Installation 07 by 97,368 BCE due to their ability to survive the effects of the Halo Array. Their cylixes were eventually discovered by Atriox during the Battle for Zeta Halo in 2560.

Background
"Halo was the Forerunners' terrible and ultimate solution to the parasite's relentless advance. Designed to destroy all sentient life, nothing was allowed to survive. And we were sure that nothing had. We were wrong."

- 117649 Despondent Pyre

The origins of the Xalanyn were unknown, but they were one of the sentient species that were extant during the fall of the Forerunner civilization. They were not indexed by the Forerunners prior to the firing of the Halo Array, and after the activation of the Halo rings, the Xalanyn inexplicably survived. During the century after the firing, the Xalanyn were discovered alive and well by the Forerunners, much to the latter's confusion.

The Forerunners and the Xalanyn arranged a parley between delegates from the two species, with Installation 07 taken into range of the Xalanyn homeworld. The Forerunners, realizing that their plan to pass the Mantle of Responsibility to humanity was in danger and treating the Xalanyn as a threat to the rest of the galaxy's species, decided that the Xalanyn were to be imprisoned on Installation 07, with some members subjugated for study at the Silent Auditorium on the ring. The Grand Edict charged Installation 07's monitor, 117649 Despondent Pyre, with guarding the Xalanyn's prison, and assigned Offensive Bias to the ring to aid in this.

However, a few Xalanyn managed to survive from their species' imprisonment, and began to roam the Milky Way in secret, visiting scattered outposts and installations in hope to find a solution in order to free their people from their imprisonment.

Return
"The Harbinger"

In 2559, the Jiralhanae Atriox, the leader of a group of mercenary raiders known as the Banished, had discovered the existence of the Xalanyn. Seeking to uncover this secret hidden by the Forerunners, Atriox and his second-in-comand War Chief Escharum travelled to Installation 07. Over the course of the conflict with the UNSC on the ring in 2560, the Banished excavated Forerunner subterranean structures, eventually coming across the cylix that contained the Xalanyn known as the "Harbinger". The Harbinger was released from her cylix by forcing a human prisoner of war, Lucas Browning, to interface with her cylix. Upon her release, the Harbinger allied with the Banished. She promised to help Escharum restore the ring to its operational status, while Escharm would help her release her fellow Xalanyn from the Silent Auditorium. The Banished excavated the Conservatory, allowing the Harbinger to gain access its interior and kill Despondent Pyre, stealing data from her at the same time. Ultimately, Master Chief Petty Officer John-117 intervened, killing the Harbinger and preventing her from releasing the Xalanyn.

Elsewhere on the ring, cylixes of other Xalanyn, though with a different appearance compared to that of the Harbinger, were found by Atriox.

Physiology
The Xalanyn are blue-skinned, gaunt humanoids with mollusk-like characteristics. They possess two arms and two legs, and their hands are tetradactyl, bearing four fingers. Their feet, in contrast to other humanoid species, project downward in a hyperextended position rather than forward, which renders them incapable of terrestrial locomotion. As a result of this, the Xalanyn rely on mechanical thrusters for movement. Their heads are smooth and hairless, with two wide-set pupil-less eyes, no nostrils, and a narrow, thin-lipped mouth surrounded by a pair of flipper-like tentacles. Their mouths contain a vaguely cephalopod-like beak in lieu of teeth, and the anterior of their lower jaw houses a single hinged, dagger-like mouthpart. This oral appendage is always exposed, and both the upper and lower lips are clefted to accommodate it when the mouth is closed.

Although incredibly little is known about their nature, the Xalanyn somehow have the ability to manipulate various forces and energy types in unique ways. The most troublingly ability the Xalanyn have, however, is a peculiar attunement to elements of Living Time itself, though to what extent remains unknown.

List of appearances

 * Halo Infinite
 * Halo: The Rubicon Protocol