I know it's only somewhat related, but on the subject of Roman slavery, there's been some interesting historical discoveries been made which I don't think have been mentioned so far in this thread. In Pompeii before the eruption, there was a Roman banker by the name of Caecillius Iucundus who lived there, and his life and that of his family has been fairly well documented. Apparently his first duty of the day after breakfast before he was allowed to do anything else was acting in the role of "Patronus", or patron, greeting any visitors that came to his house asking for help or advice, they were called called "Clientes", or clients. Many of these people had been slaves he'd formally owned. He had a legal duty to donate small sums of money to them, and give them as much help and aid they needed, financially or otherwise if they came to visit him with any problems they might have.
Also, it should be said that it was perfectly legal for any slave to buy their own freedom and become a full Roman citizen with property ownership and voting rights, all they had to do was save up enough money to do so, and their master wasn't allowed to prevent them from doing it. I don't think it was legal for Roman slave owners to mistreat their slaves either.
Slaves often had important jobs and were sometimes highly well thought of too. There's a famous stone fresco depicting the Tauroctony (Mithra slaying the bull representing the healthy control of emotions and passions, see HP HC's recent detailed post about Lord Azazel for more info about this: https://ancient-forums.com/viewtopic.php?p=287767#p287767) with the following inscription underneath:
"Soli Invicto Deo Atimetus Augustrorum Nostrorum Servus Actuarius Praediorum Romanianorum"
Which translates to "Dedicated to the Unconquerable Sun God, by Atimetus, Slave of our Emperors and Banker on a large Roman Estate". So what we have here is a likely very expensive to produce stone fresco, made for the Roman cult of Mithra and paid for by a slave named Atimetus who looked after the money on a large Roman estate.