So after my wife finished reading what I had written for the day, we leashed our foxdog (Simon Lick-a-lips Underfoot Waggletail) and went for walk as the dusk came sweeping down across the sky in a diaphonous curtain of conch shell pink. We walked down the country lane, over the bridge, and then along the reservoir. I asked some questions about what she had read, and then we reached this bit:
Me: So – what do you think of Character C? How’s he shaping up? 
Beautiful Wife: He’s… he’s kind of reserved, right?
Me: Reserved? (I blink) No, well, I mean the situation is really intense, so he’s not light hearted, but he’s meant to be more… easy going? Fun?
Sagacious Wife: Oh. Well, he’s coming across as more reserved, like a quiet source of strength.
Me: Oh. Huh! Well, OK. And, er, what about his relationship with the protagonist? Are you getting that they’re in love?
Wonderful Wife: They’re in a relationship? (my heart sinks) Oh – no. That’s, uh, not really coming across.
Me: It isn’t? I mean – well, they are. You sure that’s not coming across? It’s kind of a big deal.
Sultry Wife: No, sorry. Maybe you need to add more intensity?
Me: (crestfallen/dumbfounded, and then the penny drops and I realize I haven’t really added any romance, description, or much of anything about said character) Man. You’re right! Though he’s a main character in Book (which my wife hasn’t read). But still. I don’t think I’ve even described him yet. I might want to look into that.
Wife: (wisely just smiles and stays quiet). 
Ah! The dangers of having that richness in mind, but not putting it on the page. Still, that’s what first drafts are for, right? Catching exactly these kinds of things and preventing yourself from looking like a goof before all your Beta Readers. How fortunate am I to have such a perspicacious wife! The answer? Luckiest guy in the world.