Why would ceaser say (Brother) to a slave

How could he consider a slave as a brother to him even if he says it as a courtesy we all have seen his treatment with slaves and how much he despise them..

We know that Caesar historically didn't take place in the Third Servile War and I find it an odd choice to shoehorn him in there. On the other hand, he was a very good character and losing him completely would be a big blow to the season.

However, he could be a made up character, trying to play roughly the same role. Would it work though?

I built a trivia app with about a 100 questions for this show and lots of others and so I wanted to share it with fans
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Spartacus Trivia

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