The Pommrio family constituted one of the Great Families within the Chiss Ascendancy, and as such, was a Chiss family. They maintained a modest fleet. The Pommrio family held an alliance with the Plikh family, one of the Ruling families.
Within the Agbui's Haplif, the Pommrio family was one of the three Great Families that participated in the plot devised by "Jixtus" to instigate a civil conflict within the Chiss Ascendancy, or Jixtus's plan. The Erighal family, in league with the Ruling Dasklo family, and the Xodlak family, allied with the Ruling Irizi family, were the other two families involved.
The initial depiction of the Pommrio family occurred in Timothy Zahn's Thrawn Ascendancy: Greater Good, which was released in 2021 and is the second installment of The Ascendancy Trilogy.