Locked Out of the Loop/Playing With

Basic Trope: Everyone knows a deep, dark secret about a character...except the character themselves.
 * Straight: Alice has a dark past - ten years ago, she unknowingly slaughtered a bunch of innocents, then later forgot due to Laser-Guided Amnesia. Bob and the rest of the Five-Man Band keep this from her.
 * Exaggerated: Everyone in the Five-Man Band has some deep, dark secret - and each member is the only one who doesn't know their own secret.
 * Justified: Bob is afraid that if Alice found out about her past, she'd recreate the massacre.
 * Inverted:
 * Alice keeps the knowledge of the massacre to herself for fear that the others won't trust her.
 * Keeper of Forbidden Knowledge
 * Subverted: It seems like Bob is keeping the knowledge of the past from Alice, but that turns out to be incorrect - she knows what she did as well.
 * Double Subverted: ...To an extent. She knows she did something, but Bob didn't fill her in on all the details.
 * Parodied: The "secret" is something incredibly mundane, like Alice's real hair color. However, everyone keeps it from her with the strictest confidence.
 * Deconstructed: Alice finds out about the massacre, and proves Bob's fears right...she does recreate it, and he's the first victim.
 * Alternatively, she finds out about the secret anyway...then leaves the Five-Man Band because she feels she can't trust them anymore.
 * Reconstructed: She eventually learns about the secret, but realizes that it was kept from her for good reason, so no harm done.
 * Zig Zagged: Due to the magic of Laser-Guided Amnesia, what she knows and how much she knows all vary from time to time.
 * Averted: Either there is no secret, or she knows everything from the outset.
 * Enforced: "We need some tension among this team, and I think there's no better way to have that than there to be some secret they're keeping from someone."
 * Lampshaded: "Why is it that when I bring up the Great Troperia Massacre of '96, everyone looks uncomfortable and changes the subject?"
 * Invoked: "Look, she caused that massacre, and if she ever learns she did it, we know she'll freak out again. She can't know."
 * Defied: Bob decides to sit down and tell Alice the truth.
 * Discussed: ???
 * Conversed: "You'd think that team would trust each other enough to where there wouldn't need to be secrets."

Back to Locked Out of the Loop - just don't tell your buddy over there about that trope.