User blog comment:B214/Volume 23 discussion blog/@comment-185.112.105.215-20170419115644/@comment-29963364-20170421010034

1.) The Gremory Clan is a very "lovey-dovey" clan. They have much more friendly & affectionate personalities, and they don't distriminate their servants, Pure or Reincarnated.

2.) The Gremory Clan has a Millicas as a "fall-back plan." He can inherit the title of Clan Head after Rias retires/relinquishes it (as she did in the EX time-line).

3.) The Sitri Clan, while they may be more open-minded than most other clans (since they support Sona's dream of opening a RG school that all Devils can attend) they shouldn't be on the same level as the Gremory.

4.) The Sitri Clan doesn't have any other children to "fall back" on in terms of inheriting the clan.