That and eidolon aura's don't work if they are not your friends, or at least it says so when you can select supporting eidolon.
My Id: 65035
I will be using mainly Fafnir, although might alter it between max lb garuda and max lb Jormungandr.
Edit: Or Maybe I was wrong about eidolons auras... I could have sworn that it said so before.