OK, new theory to the pot. Richard's father isn't Daryl, but is instead a member of Daryl's clan. If Richard was born a member of his mother's clan they were going to preform the rituals to change his father to his mother's clan... but then he came out clan Daryl instead. Richard doesn't appear very magically inclined, instead preferring to use his wings, so he probably only manifested a clan mark during the exertion of that massacre, much like Dan did when he needed to reinforce his strength during his Dark Pegasus fight. That probably created a WEE bit of family tension.

Of course, that does raise the question of who Daryl's kid is, if theory number three is correct. I guess it could be Nick, by that would require Daryl randomly choosing a member of clan Jyraneth... also it would mean abandoning all the theories of Keaton being enrolled into some kind of mind wipe rehabilitation program while in prison. Sounds cruel, but it's certainly less cruel than the OTHER options I thought of how he could be Keaton's child.