I'm still not 100% sure on what "dictates" the form I'm in but there's definitely some mood stuff involved.
When I'm feeling outgoing, energetic, eager to be outdoors, I'm Werewolf.
When I'm feeling pretty/sexy, wanting to stay at home, and to an aspect motherly, I'm Renamon.
nsfw
@renbymon Can i have the first please?
nsfw
From an NSFW aspect when I'm Werewolf I'm gonna bite and there's gonna be rough sex
When I'm Renamon it's gonna be sensual sex with lots of kissing~
What's interesting is libido has zero impact on either of my forms, which I initially thought was the case; I get horny either way x)