They evolved from a prey species historically more smart than strong, more clever than courageous. This made them conflict adverse, even as they reached for the stars and ventured out into the galaxy.
Their cunning and charm made them excellent traders. And because they had no instincts to conquer or destroy, many of the sentient species of the galaxy were content to allow them access to their space.
They explored far and wide for new opportunities. It was this exploration that led them to the homeworld of the Hirudin. And, to a real extent, into their thrall.
The Hirudin used their evolved ability to control certain minds to enslave a small group of Trinax explorers. Like a virus, the Hirudin used this group to gather others, to enthral them as well.
This part of Trinax society became the servant race of the Hirudin. The fingers and feet and eyes and ears of the jellyfish-like creatures. The galaxy at large believes the diminutive humanoids are all agents of the Hirudin. In actuality, there is a duality. The majority of Trinax treat the individuals who have succumbed to mind control with pity at best and as a plague at worst.
The Trinax remain the most prevalent traders and dealers across the known galaxy. A select few even work within human megacorporations.