Sexual activity between people of different colored skin
Racial fetishism involves fetishizing a person or culture belonging to a race or ethnic group. This can include having strong racial preferences in dating. For example, an Asian fetish focusing on East Asian, Southeast Asian and to some extent South Asian women is quite prevalent in Australasia, North America and Scandinavia. There is also a subsection of BDSM, which involves fetishizing race called "raceplay".
These stories all contain people of varying colors.