I am pondering what the family tree of a tiefling might look like, and how that might change or influence that tiefer.
Lets look at the mixes.
Humans
Will mix with: Elves, Orcs, Ogres, Dragons, All known exemplar races
Will not mix with: Dwarfs, Kobalds, Thry'kreen
...okay this might take too long to really list.
Human + Lesser Taanari = half fiend
Human + Lesser Yugoloth = (not sure if possable)
Human + Lesser Baatazu =
bah can't think, will post more later.