House Nestis is an Ancient Greek-inspired Questor Mechanicus house with plenty of references to mythology and a big focus on duality. You can find more about its background here.
Enyo - Knight Errant
The knight armours Klymene and Enyo have fought alongside each other for centuries and embody the obsession with duality that permeates Janusian culture. Enyo, a bellicose Knight Errant piloted by Domina Eris, is always on the move, constantly searching for fresh targets for its thermal cannon or crashing headlong into melee. Enyo’s thirst for carnage is endless and prior to Eris’ ascension, three aspirants died in the attempt to meld with its machine spirit. Her supremacy over the armour’s machine spirit has come at a cost for it is a jealous steed – making the discomfort of disconnection almost unbearable, though the only outward sign of it is her burning gaze and haunted manner.
Klymene - Knight Crusader
In contrast to its sister-engine and as might be expected of a Knight Crusader, Klymene is patient and methodical. The armour’s teardrop heraldry reflects both the sorrow the Sito Sisterhood feels under the yoke of the Iron Fathers and the suffering that House Nestis inflicts upon its foes.
However, the armour’s sorrowful aspect also owes much to the attitude of its pilot, the supremely skilled Domina Atia. Her long list of honours, engine-kills and exemplary service has bred a burning resentment within her breast. She dreams of the devastation that she could wreck in the Omnissiah’s name while piloting a Warlord titan, but such power will forever be denied to her by the simple and arbitrary impediment of her sex. This bitterness is compounded by witnessing the follies of her two sons, Atlas and Prometheus, princeps of the Warlord Titans, Back-Breaker and Flame Eternal, respectively and the bloody rampages of her older sister, Domina Leda, aboard the Knight Valiant, Tisiphone. When Atia dwells overlong on this injustice, Klymene is prone to glitching, its hurt pride spilling out from the throne mechanicum as auspex-ghosts and grinding gears.