I am basing it at least somewhat on traditional Thieflings, sans horns. Thieflings are obviusly demonic on any sort of observation. Like the silver lines, wierd gloweing eyes, strange ears and complexion of my charachters. Others have horns and goatees, or other obvious demonic markers. Thieflings cannot hide what they are. It is one of the reason very few of them actively pursue criminal careers. Becouse people will point and scream "DEMON" xD.

Succubi would be more pure temptation if anything. subtle influences and tricking the brain trough more subtle ways then illusion.

I basically approach halfbloods like this: If you not making both parts of the heritage obvious on first sight, then don't go half. xD