At the end of the day, they're just two sides of the same coin. Getting what we want.

Reason and rationality is the slow long term view of getting what we want, while emotion is the fast hot immediate view of what we want. The latter informs the former - when we step back, we consider the potential gain and loss through all possible emotional outcomes, not just the active one.

But they don't exist independently of emotion - that is still the thing that gives you a desire or drive for anything at all, and keenly relates to helping achieve your homeostatic and reproductive outcomes (i.e. surviving).