User blog comment:Merkarion/Original Gremory Clan Ability/@comment-33341107-20181219091528

I think it's to do with flora. When I looked into the demon Gremory from the ars Goethia I found he had an association with camels, woman and lust (the last 2 virtually all demons in the ars goethia have an affiliation with) but nothing about roses, their clan symbol. If it's plant based that means it has a connection to life which is why I think that Milicas and Rias didn't inherit it, their mother/grandmother's power conflicts with Zeoticus' so they inherited the clan trait from the more powerful parent (Venelana). The reason Sirzechs can use both is becauses he's a super devil but the power of destruction is the more useful ability to use in combat. Something else that makes me think this might be the case is that it reflects the current generation of Bael's and Gremorys,Gremorys are supposed to be life but both Rias and Sirzechs have inherited destruction while Sairaorg didn't inherit POD and his brother is weaker at it than Rias, but Sairaorg uses Touki which relies on his LIFE force while his brother is a skilled botanist (works with plants).