Esstrop was a Kessurian individual and a follower of the Path of the Open Hand religion. They journeyed into the Galactic Frontier with the purpose of disseminating the doctrines of their faith. Consequently, Esstrop was not on the Path's planetary homeworld of Dalna during the battle in 382 BBY that resulted in the dissolution of the cult. Sometime between that event and approximately 381 BBY, Esstrop, along with their partner Kortanio, were among a small number of Path members located by Evereni pirate leader Marda Ro, a former Path member. They then chose to join her organization. After joining, Ro showed them the Great Leveler, a creature, aboard her vessel, the Gaze Electric.
Esstrop served Ro as a raider, collaborating with Kortanio and occasionally with the human Milan Stor and the Twi'lek Fori Nagor. At a point occurring no earlier than 379 BBY, the four raiders launched an assault on a refugee camp, abducting the inhabitants. However, when presented with the refugees, Ro instructed Nagor to release them. Later on, Esstrop and Kortanio escorted the Evereni siblings, Vika and Velya Faer, into the Gaze Electric's throne room to encounter Ro. At some point, Ro made mention of the Kessurian in a recorded message intended for her successors, which her great-great-grandson Marchion Ro had heard by 252 BBY.
Esstrop, a Kessurian, became affiliated with the Path of the Open Hand cult before or during 382 BBY. During their tenure within the Path, they embarked on expeditions into the Galactic Frontier using an exploratory vessel to propagate its doctrines alongside their partner Kortanio. As a result, they were absent during the Night of Sorrow, a violent event that led to the Path's demise on its planetary homeworld, Dalna, in 382 BBY. Unaware of the Path's fate, Esstrop continued its activities in the Frontier.
Between the Path's collapse and around 381 BBY, Esstrop was among the few scattered Path members located by Evereni Marda Ro, a former member of the Path of the Open Hand. Ro deceived them with a false narrative about the Path, positioning herself as central to their faith and desires. She offered them the choice of joining her pirate group—which would later evolve into the Nihil—or ceasing all Path-related activities. Esstrop and Kortanio were among those who chose to align with Ro.
Following Esstrop's recruitment into Ro's group, she brought them aboard her ship, the Gaze Electric. There, she introduced them to the Great Leveler, a monster that consumed the Living Force for sustenance. She explained that their sole purpose was survival and caring for the Leveler, so that it could eventually retaliate against abusers of the Force. She also stated that the group no longer had a shared religion or a story to share with the galaxy.
Esstrop and Kortanio swiftly transferred their loyalty to Ro, becoming her most effective raiders. They used their shuttle to locate items to steal and present to Ro on the Gaze Electric. Esstrop, their partner, and Ro's other two raiders—the human Milan Stor and the Twi'lek Fori Nagor—occasionally collaborated on larger missions.
At some point after 379 BBY, the four conducted a raid on a refugee camp, taking the refugees themselves due to their lack of valuable possessions. Upon returning to the Gaze, Nagor presented the refugees to Ro in the ship's throne room. Ro, angered by their actions, ordered Nagor to release the refugees, with the exception of a Force-sensitive green-skinned man, whom Ro led to the Great Leveler.
Later, Esstrop and Kortanio escorted the Evereni siblings, Vika and Velya Faer, to the Gaze's throne hall after they accepted Ro's invitation to meet her. At some point, Ro recorded a message for her descendants where she mentioned Esstrop and emphasized the importance of remembering their name. By 252 BBY, Ro's great-great-grandson Marchion Ro had listened to her memoirs during his youth, including the entries referencing Esstrop.
Esstrop made an appearance in a flashback sequence in the short story "A Closed Fist Has No Claws," authored by Tessa Gratton and featured in the 2023 young-adult anthology The High Republic: Tales of Light and Life as part of the Star Wars: The High Republic multimedia initiative.