Firenewts

Firenewts are a race of sapient peoples native to the great northwest desert now known as the Glassed Expanse. In the last four centuries since the fall of Embrek-Yed-Al, the Imbued Enchantment which felled him has slowly grown over the entire desert. Rather than being a simple deathly-hot desert dotted with beautiful oases, the entire region has been fused together into a single sheet of glass. This has notably displaced thousands of the previous denizens, most notably among them the firenewts. They have fled to the adjoining regions, attempting to integrate into local landscapes and what few civilizations are located near the border of the desert.
Firenewts are a culturally diverse species, speaking multiple languages and exhibiting a penchant for storytelling. However, perhaps the most notable part of their culture is what they call their "terms of righteous repayment," a system by which they repay debts. If one performs a favor for a firenewt, they are culturally obligated to repay that favor fivefold. Which is to say, if a firenewt were unable to feed their family and were given enough food for a day, then they would be obligated to provide five times that amount to their benefactor.
This could be in terms of simple repayment, kind for kind - 5 days of food, for example - or monetary value - 5 times the cost of that food in gold - or performing a task which is of equivalent value - serving the benefactor for an amount of days of equivalent value. There are a host of qualifications to this, of course. Notably, the favor must be performed without the intention of being repayed. Firenewts seem to have some sort of extrasensory perception about this. This also does not apply in standard business transactions or contracts. Also, the favor must be meaningful. If that one day's worth of food does not help the firenewt's family survive the winter, then the firenewt is under no obligation to repay the debt, and the favor is then viewed as wasteful.
However, there is one significant factor to this cultural norm: In fleeing the desert during its glassification, several hundred - perhaps near a thousand - were taken in by each city. Their lives were saved by the generosity of the city's denizens and its leaders. Now, because of the terms of righteous repayment, they are obligated - even several generations from when it began - to uphold the favor they owe, of saving the lives of nearly 5,000 citizens of the city. The cost of such a debt is incredible, as they consider the life of an individual to be entirely uncountable. Thus they now live in servitude, hoping that by doing so they can save enough lives to be free of the debt.