It is now unknown which founding they are from (many now say it was from the ill-fated 21st), all that is known is at one time there was much hope for the Chosen known simply as the Huntsmen.
Their Geneseed is said to be a combination of the Space Wolves and Dar Angels and was made so to maybe bridge the differences between those two chapters. Others disagree and said the gene splicing was from a number of Geneseed. All that was known is that they had an extreame hatred of Tyranids and could battle these creatures very well.
For over a hundred years they served the Emporer, mainly in tasks that best suited their abilities to 'sniff' out Tyranid Hives and the place of origin. Thanks to them, may planets have been spared destruction by the swarm or by the Imperium cleansing an infected planet. Then they came to Requiem IX, a small forested planet just outside the border to the Maw.
It took less then a month for them to exterminate the Hive on that world and while most of the chapter was entrenched on the planet waging the final assaults the Huntsmens doom was sealed as a Tyranid 'Fleet' somehow entered orbit undetected and destroyed all the ships the chapter had in orbit.
The Companies on the planet were baffed on why they had lost upbrupt and total contact with their brothers in space. They sent contact to the Imperium for pickup when the trap was sprung. Colonies all over the planet showed their true loyalties as they were infected by Genestealers as the orbiting Hive "fleet" started deep-striking the planet. The Huntsmen were heavily out numbered and seeminly cut off from any hope.
That is when the first whispers started......
Nurgle was first, promising those fallen and infected. Promising them that they wouldn't become part of that what they most hate. Promisig them revenge.....for a price.
Then Slaanesh joined in, tickling the euphoria of those who got a thrill of prolonging the pain of the xenos. He showed them how to prolong that torture and how to recieve pleasure in it.
Then Tzeentch joined the cacophany of chaos. Showing those with psychic abilities powers and rituals to attack the swarm and to turn it against itself.
Finally Khorne filled the remaining few with sounds of wardrums and visions of a carnage of tyranids.
All the Gods of Chaos won Favor with the Huntsmen that day an the battle quickly turned. Nurgle, with the majority, raised the dying and infected to attack the hives rearguard. Slaanesh turned pain into pleasure to the frontguard, causing them to relentlessly push forward. Tzeentch gave the Librarians spells that turned the Tyranids most powerful warriors into shapless blobs that attacked their former kind from within. Finally Khorne, who had caught the Force Commanders attention, came through on his promise, filling the leaders body with chaos, mutating him into a Beast of WAR to lead the other Khornite recruits to charge forward and destroy the creatures that controlled the Hive.
When the Imperium finally arrived, they found one living being on the planet. One very mutilated, tortured, and battered Champlain Neophyte who spoke ten words before the pain made him pass out. He said, "My Brothers have turned, they now Hunt us as well!"
The Huntsmen now Hunt in the name of Chaos! Ultimately the Tyranids are still their greatest sport, but now they claim trophies from the Imperium of Man as well.
As for the lone Neophyte that was sparred to send the message, it is said he now serves either Deathwatch or the Grey Knights but always has a watchful eye for his former Battle-brothers so he may set their souls free.......