The Blood Axes are a massive, galaxy-spanning Ork Clan and the first of all the great clans to encounter the Imperium. As such they have a much better grasp of human-style tactics & values and are known to engage in trade and even mercenary work with humans.
Such behaviour is treated with disdain by most other orks, who are therefore loathe to fight alongside Blood Axes and will not hesitate to fight with them should no better target be available.
Blood Axes in Sector Deus[]
Blood Axes have been present in Sector Deus just as long if not longer than the Imperium, and their stronghold in the Sector is the planet of Pexar in Subsector Aeternus. Here they operate a crude imitation of a vaguely-Imperial society, mixed in of course with the near-constant brawls and violence that ork civilisation is built upon.
Chartist vessels are known to be a frequent occurance in the orbit above Pexar, the distant world made readily available by the extensive warp routes Subsector Aeternus is known for. These chartists trade various Imperial-made goods to the Blood Axes in exchange for "shoiny metal an' sparkly roks" the orks pull out of the ground.
In addition, Rogue Traders and even Imperial officials such as Inquisitors are known to visit this world to contract the services of Blood Axe mercenaries. These orks are popular to use because not only are they savage, cunning and effective fighters, but they also offer total discretion because they do not care to remember any details of their mission beyond what the biggest thing they killed was.
There are however two big downsides of using Blood Axe mercenaries.
The first is that of spore contamination. Orks must not under any circumstances be taken to planets that have yet to be infected by ork spores, and to do so would be to invite the most terrible retribution from the Administratum, the Inquisition and the planet itself. And even if kept confined to voidcraft the ship must be extensively purified once the orks have departed.
The second downside is that the orks have no set price. One year a mob of Blood Axe Kommandos might demand a dozen plasma guns as payment, the next year they could be demanding "one o' dose waaaghlord titanz we saw last time you 'ired us".
But if these downsides can be accepted and mitigated a mob of Blood Axe Kommandos can be the finest soldiers-for-hire in the sector. Each one is a natural born killing machine infused with a desperate hunger for battle and victory who will charge through a torrent of fire, come back missing several limbs, and thank their employer for bringing them to such a good fight. Though of course there are no guarantees a mob of Blood Axe mercenaries won't simply turn on the same people who hired them if they think they can win.
Perhaps the most famous use of Blood Axe mercenaries in the recent history of Sector Deus was durinng the Third Ionian Crusade, when a specially adapted Imperial Navy heavy transport disgorged almost ten thousand Blood Axes into a powerful defensive space station over Axis Mundi that was preventing the Imperial Fleet from performing exterminatus on the world. Within a matter of hours every traitorous human on the station had either abandoned it or was dead, and the orks voxed report consisted of "all dem 'umies that you 'umies dont fink is propa 'umies iz gone now. Me an da boyz gonna take our loot now den you can take us home".
Twelve hours later the once powerful station had been reduced to almost a bare spine with everything of either technological or aesthetic value looted by the orks. The original plan of the Imperials was to destroy the transport with all the orks aboard once they had outlived their use, but one cunning Inquisitor stayed the Imperial Navy's hand. During the raid the Kommando leader named Fragmakka had acquired vast amounts of flashy bits, and the Inquisitor knew such wealth and technology would quickly make him warboss of all Pexar. The Inquisitor gave Fragmakka a bonus payment of a million teef pulled from the dead jaws of the feral orks of a recently purged planet, and even invited the Kommando to a formal dinner.
Over the dinner Fragmakka consumed several whole groxes (and insisted on fighting a live one, before eating that too), and though throughout the entire meal the Inquisitor had one hand on his plasma pistol something that could perhaps be called an understanding formed between the ork and the human. Fragmakka would return to Pexar with all his loot and take control of the planet, and in return for staying there the Imperium would hire them for the best fights and wouldn't bombard the world to oblivion. Fragmakka agreed with the terms, and since then the Blood Axes of Pexar have been used by the Inquisition for a number of operations no one else ever hears of.
Though Fragmakka rules Pexar to this day, his distinctly un-orky attitude over not trying to build roks to attack other worlds has riled up many orks. Though he has crushed every openly defiant Nob Fragmakka cannot live forever, and the Inquisition maintains a small listening post on Pexar's moon in case the 'moderate' warboss should fall and be replaced by a more hostile greenskin.