In Xmen the animated series, that ran from 1992 to 1997 on Fox Kids there were several incidences of slavery. There is even a mention of a love slave and this show was targeted to children.
In the episode slave island in the first season, Gambit, Storm and Jubilee go to Genosha where they are forced to become slaves. They are also forced to wear slave collars which show up in later episodes.
In captive hearts in season one Callisto of the Morlocks tries to keep Cyclops as a love slave. She says that she wants a strong man who doesn’t nessarily have to fight, because all she wants from him is an heir. Children don’t know what love slaves are and don’t need to know about them either.
It’s good for children to know about slavery and that its wrong, but they shouldn’t know about love slaves. Mostly that went over the heads of children, but is it a good thing to show kids something over their head in cartoon? Its fine for a cartoon that is not targeted to children, but X-men is.
Was X-men originally supposed to target teenagers and was given a time slot for children just because it was a cartoon? It did air before adult swim, so maybe they didn’t know they could market cartoons to teenagers and adults.