>One of them is a witch with no sense of proportion, and the other is a
>mercenary shrine maiden.* Neither one really goes in for moderation.

Even better, later games mix in some combination of characters you've previously fought as playable choices, and their motivation is similarly suspect:

*Remilia joins the case out of sheer boredom
*Sanae Kochiya is a newcomer shrine maiden (as in packed up bags and moved from the real world into Gensokyo) and is trying to outdo Reimu in order to get more followers for her shrine
*finally, there's Youmu Konpaku, a half-ghost who serves as the Token Serious Person in all of this. She also has a sword technique that sees her move an appreciable fraction of the speed of light for the duration.

"This is probably a stupid question, but . . ."