Essteeoh was bell-shaped and had four server arms and fine work manipulators, originally being a medical droid in the Emperor's employ. How Chabak, the original owner of Chabak's came to own the droid, which had been used by Palpatine's personal doctor in Imperial City, remained unknown.
Chabak modified the droid's pharmaceutical procedures into programs allowing it to mix beverages from all over the galaxy. Only Quink, who found the droid's original programming procedures in a safe, knew about Chabak's secret.
Esteeoh was aboard Zirtran's Anchor when it disappeared, but claimed to have no knowledge about what happened. It eventually started speaking gibberish about rows of medical tanks and other strange things. It remained unknown whether this had anything to do with his former job as a medical droid or whether it was caused by the mysterious disappearance of the space station.