As the wikipedia page explains in the early republic and before the last days of the republic most slaves were conquered slaves. However that supply dried up quite a while before the first emperor.
After that, most slaves in Rome were people that had sold themselves into slavery (or were sold by their parents) and by the time Rome was a real republic this had term limits, as well as rights, starting with the basic right to challenge their status in court. Over time, more rights were granted. Read on in the wikipedia article, it does talk about this.
> Over time, however, slaves gained increased legal protection, including the right to file complaints against their masters. Attitudes changed in part because of the influence among the educated elite of the Stoics, whose egalitarian views of humanity extended to slaves.
(this is not talking about the right to challenge their status, this is about filing complaints, eventually even against "cruel treatment" and so on)
From that same page, the "conclusion" if you will, the standing slaves had by the end of the empire.
> Several emperors began to grant more rights to slaves as the empire grew. Claudius announced that if a slave was abandoned by his master, he became free. Nero granted slaves the right to complain against their masters in a court. And under Antoninus Pius, a master who killed a slave without just cause could be tried for homicide.[71] Legal protection of slaves continued to grow as the empire expanded. It became common throughout the mid to late 2nd century CE to allow slaves to complain of cruel or unfair treatment by their owners.[72]
I am not saying Roman society was just by modern standards, it was not. I would mention though, especially in the east, but also in the west, it was far better than what was to follow. And, as the wikipedia article mentions, in Rome at least (and presumably in most large Roman cities) it was a better fate to be a slave than to be a free urban poor. To be a (voluntary - not a convicted) "public" slave came with pretty good social standing.
The section about Asclepius mentions a few of the horrible things Rome did to slaves, especially earlier in the republic.
Come on, stop bullshitting.
Just see Wikipedia for a start: Slaves were considered property under Roman law and had no legal personhood. Unlike Roman citizens, they could be subjected to corporal punishment, sexual exploitation (prostitutes were often slaves), torture, and summary execution. https://en.wikipedia.org/wiki/Slavery_in_ancient_Rome
Slaves did not usually have contracts. It was possible to sell yourself or your kids into slavery, but slaves were usually taken from conquered peoples and sold on the market. They had no say in what they would be used for. They were not automatically freed, and children of slaves became slaves. I don't know if owners would kill their slaves for fun - they were expensive property after all - but under Antonius Pius it became illegal to kill slaves without "just cause". Which means until then it was fully legal to kill your slaves for fun.