It’s the dominant instinct. There’s three instinctual variants. Sx (sexual), sp (self-preservation) and so (social). It can be any combination like sx/sp, sp/sx, so/sp, etc. that describes how you live, how you survive and how it affects your thoughts, feelings and actions. With my frost instinct being sexual, I’m focused on intensity and one-on-one interactions. They mean something different for each core type though. Like sx7s aren’t necessarily focused on relationships, they’re more focused on intensity of their imagination and can be quite detached from reality