When considering the name "the Dark Urge," my initial thought was of someone grappling with the choice of succumbing to or resisting the temptation to do wrong. While this concept could have potential depth, it appears that players currently have too much control over resisting the urge.
Opting to yield to the Urge should remain an available choice without requiring ability checks. However, choosing to resist the Urge should ideally be the primary action players face when encountering the Dark Urge dialogue options. This change would more accurately convey the internal struggle with these urges.
Upon initiating conversations, when the list of options includes traditional choices, racial options, and new dark urge-related options, the game should automatically mandate a Dark Urge check for these specific options. Failing this ability check would result in immediate succumbing to the urge as indicated by the dialogue choice.
This approach might not suit everyone, especially those who dislike this level of vulnerability tied to a character named "the Dark Urge," but let's face it, you shouldn't be playing this character if that's the case. Conversely, if a player successfully resists through the ability check but later decides they actually wanted to give in, an option free from ability checks to yield to the urge, could remain available amidst the other dialogue options.
This, in my view, presents the most genuine and engaging means of representing a character grappling with dark impulses.