User blog comment:AquilaeAltair/OnS Theories (5S) - Third Theory - Rigr’s weapon: An incomplete seraph/@comment-36009152-20190820011538/@comment-38762161-20190903035126

Hm, I wouldn't call him a human but he's not a vampire; it's more like he's more like a cursed gear with a real body and so on with certain touches of a seraph; since he can drink blood and demons tend to drink blood in order to boost their owners; it's possible that that might be the reason as to why Rigr is more lively compared to Urd.

Likewise, I could be wrong, still, I somehow believe he won't reach the victory but instead just make Sika Madu be proud or at least see him as a foe or threat