Lin Yuan was aware of Fan Lou's capabilities.
Lin Yuan used Fan Lou because he wanted Fan Lou to work for him. As long as Fan Lou worked for him, Lin Yuan would give him benefits and would not make his life unnecessarily difficult.
Even if Fan Lou made a mistake, he could just eliminate him.
Fan Lou's worries were unnecessary.
If Lin Yuan wanted Fan Lou to complete a task, he would do his best to pave the way for him.
The Dark Pufferfish would not trade their poison to the Bloodians in a one-time deal. When Fan Lou returned, there would be two Dark Pufferfish going with him.
These two Dark Pufferfish experts would interact with the Bloodians and name Fan Lou as the liaison to the Dark Pufferfish.
This way, Fan Lou would be able to successfully become acquainted with the Bloodians and would also become more important to Feng Qing.