User blog comment:Merkarion/Original Gremory Clan Ability/@comment-31137559-20181219031426

Power: Extraordinary affection for their servants.

Again we've been over this already. If the House of Gremory had a special ability, it would have been revealed by now.

Basically every high-class devil house has high demonic powers. The House of Gremory isn't special in that regard.

Sirzechs' superior control of his demonic power is his alone. He excels in the technique department like Sona and Ajuka when it comes to using his demonic power. Having superior control of your demonic power is something a lot of devils have which includes those like Sirzechs, Ajuka, and Sona.

And the House of Gremory wasn't even a major house of the 72 Pillars originally. They really only rose to fame because of Sirzechs. And that was because of his extraordinary demonic powers(which has nothing to do with your house) and his Power of Destruction(which he inherited from his mother who's from the House of Bael).

Just because they were the first house of the 72 Pillars introduced and they're a major part of the series doesn't mean they have a special ability.

Just because we see some devils of a specific bloodline having some unique special ability doesn't equate to every devil of a specific bloodline having a special ability.