I saw this information on a writing message board and it made a lot of sense to me. Thought I'd share.
...many books include a "mirror character" whose main purpose is to act as a sounding board for H or h (H refers to the hero and h to the heroine). Best friend, sibling, whatever. The idea is that you take the interior monologue and shift it into a dialogue scene between the mirror character and the H or h.
It's more active than straight interior monologue, but more static than an action scene. They're just talking their way to a decision, after all. Not really doing anything, like chasing the bad guy or excavating a mummy -- not being active, but being reflective out loud.
I try to limit my interior monologue as much as possible because it slows down the pace. If it can't be done, a mirror character is a good way to make it pacier. Give them something plot-related to do while they are having their talk, and it picks up even more.
OTOH, romance readers have come to expect a certain amount of introspection, because of the genre focus on internal conflict.
All of which is just to say, a small amount of interior monologue is a good thing. Larger bits might be better placed in a scene with a mirror character -- or find some other active way to communicate the character's evolving frame of mind (heart?).
