Though Imperial Commanders in the Eastern Fringe are rightfully wary of Tau expansionary forces, they have sometimes been forced to ally with the xenos in order to overcome adversity. When such an abhorrent compromise is required, it is frequently the Scions of the Militarum Tempestus who are rallied, in no small part due to their willingness to adhere rigidly to Imperial orders without argument. One regiment that has won much honour while fighting alongside the Tau is the 86th Deltic Dragons. They have gone to war several times alongside the Fire Warriors and Tau Battlesuits of Kel'shan Sept. That this sept's fighters show a similar level of determination and stoicism to the Militarum Tempestus is purely a coincidence.
Standing together, the Scions and the warriors of Kel'shan Sept defended two worlds successfully against splinter fleets of Hive Fleet Gorgon. In each battle, the 86th Deltic Dragons were able to take advantage of the Fire Warriors' covering fire when making swift strikes against larger targets, while the Scions' resilience when fighting at close range bolstered the Tau lines. The complementary nature of the two factions has proven of great interest to the Ordo Tempestus, who monitor their alliance closely -- other than in directing battlefield orders and relaying status updates, Tempestor Prime Prellus is forbidden to engage in dialogue with the Tau Commander Shas'O Shi'Y'he.
The Tempestus Scions of the 86th Deltic Dragons primarily wear dark grayfatigues, with black camouflaged Carapace Armour in brass trim, as well as a black right poleyn (knee guard), Slate Monitron and Omnishield Helms. The left poleyn (knee guard) and gauntlets are red. The left couter (elbow guard), vambrace and pauldron (shoulder guard) all have red chevrons that adorn their surfaces.
Chevrons adorn the armour and vehicles of the 86th Deltic Dragons in ever changing signifier-patterns that only they fully understand. This is an intentional ploy, intended to obfuscate regimental hierarchy and symbology from the watchful eyes of the Tau with whom they have forged frequent -- if uneasy -- alliances.
- Codex: Militarum Tempestus (6th Edition), pg. 28