@versub @Petnavis
I believe it was portrayed in the first few chapters is treated like a lifelong job your chosen for (aka it's similar to pre medevil slavery minus some exceptions like the spartans), something similar to a butler or rarely, bodyguard, like wals case, if it's like the past, it's basically not really as bad as it sounds, the worst part of it is your bound to your job until your unable to, and in ancient times where things were really bad, some people voluntarily became slaves in such a manner as it guaranteed room and board, so it's not entirely right to think of it with modern lenses, that said we might find it problematic, but historically this was far from uncommon, and slaves that served such a master would in fact, consider such a great honor and fight to the death for them, so wals actions are quite realistic, if he wasn't reincarnated of course.
Oh and such slaves can be freed if they prove themselves worthy of such, even becoming nobles themselves and sometimes the slavery contract was temporary, something that is also uncommonly known these days, slavery for life was usually only reserved for war criminals in ancient times, otherwise freedom was possible for most.