Thanks all for the feedback on the original idea, quite agree with most of them.
Maybe i was exagerating a bit that the first tieflings look dangerious (they indeed look more scarred) however, minor knowledge checks could be useful for lot of background info, beyond just the tieglings. The way these checks are implemented is already very solid (just a quick line of dialogue, so that wouldnt require much work). Also making some rolls like history or religion a bit more useful.
