Xaku

Xaku is the first frame the archive files with no gender at all — they, them, a plural made singular. And the plural is literal. Xaku is not one Warframe but the broken remains of several, drawn together and held as one being by the Void that binds them.

There is no Leverian for Xaku, and no need to invent one. Their origin is told plainly on Deimos, at the close of the Heart of Deimos, by the Entrati Grandmother — who looks at the composite thing the Tenno have assembled and recognises it as kin: a sum of many, a family of its own.

Across the long ages the Entrati kept their vigil on Deimos, broken and abandoned frames drifted lost in the Void. Their pieces were drawn together and fused — "driven by void spirits," as the Drifter puts it — into one corporeal will. Three, by the Drifter's count, though the archive holds that number as attested-but-second-hand; the plain description says only "broken Warframes," plural and unnumbered.

What emerged wields the Void as its weapon: cloaking arms in Void-fire, tearing guns from enemy hands to hang and fire them, wearing three borrowed powers under the ability named, exactly, The Lost. One of those beams even strips a Sentient of its resistances — the Void doing to them what it was always the one thing that could. That the dead frames fell in the Old War is a fair guess and no more; the Grandmother says only that they were lost in the ages, and the archive leaves it there.