On the TV show Highlander, that is. Specifically, I’m not clear about the one rule that appears to be carved in stone: that the Immortals don’t fight on holy ground. Sure, it’s disrespectful to God to fight inside a church, but there has to be more to it than that. It seems like no Immortal, no matter how evil and amoral s/he is, is willing to fight in holy places. Is there some kind of punishment for breaking this rule? Or is it just a taboo so strong that not even the bad Immortals are willing to break it?
From what I recall of the film(s), The santity of “Holy Ground” is a convenience which allows the immortals to meet or rest without fear of attack, the sanction being, presumably, that any immortal who abuses this term opens themselves up to similar attack from all or any of the others (no rest, no hiding place).
Regards
Walrus
In the first movie, Ramirez describes it as a tradition that all of the immortals will respect.
In the third movie, Connor and the villain try to start a fight in a Buddhist shrine. The shrine starts glowing red, the icon gets an angry look on its face, and the fighters hastily call a truce.
In the TV show, Joe Dawson tells Duncan that no one really knows what might happen, but there is a rumor about two immortals duking it out in a shrine in Herculaneum just before Mount Vesuvius erupted…
The sequels to “Highlander,” as evidenced above, are a perfect example of how you can over-explain a story.