"Like motes of dust in a beam of light, the lives of men are fleeting and aimless. Where the humans flounder and fail against the fates, however, the Eldar tread carefully along the crooked path, each foot fall a moment in time, each stride a step closer to the opening of the way."
- —Syndilian Shanyr, Eldar Pathfinder
He has been sent by the Farseers of his craftworld to prevent the fulfillment of an ancient prophecy predicting that a gateway to the heart of the galaxy in the Eastern Fringe would be claimed by a malevolent force.
As such, he has been identified as a high-priority target by the Deathwatch of the Reach.
The Imperium has precious little information on the presence of the Aeldari in the Jericho Reach. Beyond the presence of a few corsairs and xenos pirates, such as the Black Prince of Slinnar or Qulisanna's Blade, it is largely believed that no significant Aeldari threat exists.
This of course is far from the truth and the Craftworld Aeldari, the Asuryani, have long had eyes watching the Reach, moving in the dark and keeping vigil over its dead worlds.
Among these Aeldari scouts and spies is Syndilian Shanyr, called "Syndilian the Traveller" among his kin. Syndilian and others of his people undertook the epic journey through the Jericho-Maw Warp Gate and into the Jericho Reach at the behest of their Farseers.
This was a result of what would become known as the "Prophecy of the Crooked Path," laid down by the Farseers of Craftworld Il-Kaithe hundreds of Terran years ago, and identifying the role their people would have to play in this region of space.
It was seen by the Il-Kaithe Farseers that a time would come when a great enemy would rise in the Eastern Fringe of the galaxy. Aided by the forces of discord and destruction, it would lay claim to a gateway to the heart of the galaxy, a gateway the Humans would be powerless to defend or to close.
It was a fate, however, which could be averted -- if the enemies of the Aeldari could be turned in upon each other and time could be won to close the gate themselves. This lofty task is why Syndilian has spent much of his life moving silently and unseen between worlds with his cadre of elite Rangers.
Using the wisdom of the Aeldari and his own cunning, Syndilian has been subtly influencing events across the entire Reach, instigating battles, assassinating influential targets and even creating alliances between enemies -- all for the purpose of prolonging conflict.
Most recently, Syndilian and his followers have been operating in the Orpheus Salient of the Achilus Crusade, meddling with the course of events and the advance of Hive Fleet Dagon. Before her death, Inquisitor Kalistradi of the Ordo Xenos had even uncovered some evidence of the Aeldari's presence on Avalos, though this has since been lost during the bloody course of the Tyranid invasion and her own demise at the hands of the Lordsholm Broodlord.
Syndilian Shanyr is an extremely dangerous foe with Terran decades of training and experience in stealth and subversion. It is for this reason that only the tiniest whispers of his presence have ever reached the Imperium, and even the Inquisition has only the vaguest information on him -- little more than a name and some sketchy second-hand reports of a deadly Aeldari assassin.
What worries the Inquisition and the Deathwatch the most about Syndilian, however, is not the lack of information on him but rather the fact that they have no clear idea of the nature of his mission. In their eyes, the Aeldari seems to appear at random, killing, sabotaging, or otherwise altering events often without any clear short-term effect.
While the damage he has inflicted seems limited, he has still been branded as a priority target and dangerous xenos terrorist by the Deathwatch. Kill-teams dispatched to areas where he is thought to be operating often have Syndilian's assassination given to them as a tertiary mission objective should they chance to encounter him.
To date, however, Syndilian has yet to be cornered by a Kill-team, and his few encounters with other Imperial forces have been brief and very one-sided.
- Deathwatch: The Achilus Assault (RPG), pg. 141