Well, I think the variants are meant to work along with the enneagram. Here is a site that is fairly descriptive on the matter: http://www.ocean-moonshine.net/. If you look under the Instinctual subtypes section, you can find info on the instinctual subtype of your enneagram type, ha. Anyway, I think it's just as valid as any of this stuff is really, which you know... obviously doesn't mean it's scientifically proven. I can apply it to myself and others, but it took time. I personally know that I am a sx/sp and that it is not going to change. It explains a lot of my moods/behaviors/impulses. I see I relate least to people with sx last in their stacking. It all made sense in time for me. Anyway, check out that site and see if it clears things up for you.

 

^ true, but the interesting thing I've discovered is, when I see other INFPs' instinctual variants, very few are sx/so or so/sx <-- I'm actually one of those, just not sure which one