Familiars
From OMGWiki
Familiars are sort of like "Angels" for demons. As we see in chapters 170, The Great Earth Search, and 171, Kiss Me Goodbye, demons can have angel-like entities (I don't want to say that they are the same as Angels, because we simply don't know), called Familiars. To explain all this, let's recap what Hild's experiment entailed. She wanted to know if a goddess could turn into a demon. To accomplish this, her plan was to rip out a goddess's Angel, and then implant that goddess with a demonic Familiar. This was carried out on Belldandy. Not only did this plan fail, but it had an unintended consequence. The Familiar turned into an Angel, but still retained Familiar (demonic) blood. It became righteous. More interesting was that Keiichi was able to have this "angel" in him, which was later transferred to Velsper, which is even more interesting! Velsper is a demon and the Angel is just that...an Angel. Bell even compliments K for referring to this Angel as such, and not as an "ex-familiar". So, into Velsper went a righteous Angel that retained familiar blood. Now, this is not the same as Urd's situation. Urd is one, with two different "blood types". Velsper and Die Wespe der Blauen Lanze are two separate entities. Figure that one out.
Now, as to whether or not demons need Familiars, if Familiars have elemental designations like Angels, or how they interact with their demon host, are complete mysteries.
