Knight in Sour Armor/Playing With

Basic Trope: A cynical character who is nevertheless obstinately good.
 * Straight: Carol Lime is an experienced police detective who honestly expects most of her cases to end without resolution ... but not for lack of trying.
 * Exaggerated: Carol is an Iron Woobie who is constantly undermined by those around her.
 * Downplayed: Carol is sarcastic but not particularly pessimistic.
 * Justified: Most of her cases have been long-dead or badly prosecuted.
 * Inverted: Carol is an up-and-running villain filled with idealistic zeal of how easily she's going to Take Over the World.
 * Subverted: The Reveal is that Carol is actually a Dirty Cop.
 * Double Subverted: ...except she was framed.
 * But that was in the past and they are trying to make up for it.
 * Parodied: Carol is continually ranting about how Being Good Sucks and Humans Are the Real Monsters, while at the same time stepping in to save every person she can and screwing the rules and the money to do what she thinks is right.
 * Deconstructed: The work goes on about how Carol's dedication to justice with little reward is wearing away at her enthusiasm, and she begins wondering if it would be better to falsify some evidence just so she can have something to show for her hard work.
 * Alternately: Remaining obstinately good feels good, causing her cynicism to slowly ebb away into a more idealistic mindset.
 * Reconstructed: ...but she is reminded by her friends that the world needs her and that they believe in her good moral core. It gives her the strength to continue to work hard regardless of success or failure.
 * Alternately: ...but her new found idealism causes her to become overly-invested in a particular case, which she is unable to close. This causes her to remember that while having hope is good, she still needs to keep her professional distance or she'll compromise the justice she wants to bring and risk giving up all together.
 * Zig Zagged: ...but the framing was actually a lie fabricated by Carol in order to hide her True Colors.
 * Averted: Carol is cheerful and optimistic.
 * Enforced: True Art Is Angsty.
 * "The world can suck at times, People need a hero who realizes this and fights on regardless."
 * Lampshaded: "Why do you fight so hard if you know you're just going to lose?"
 * Invoked: "I Gave My Word."
 * Exploited: Carol is assigned the case because the criminals are more likely to mistake her for someone who can be bribed.
 * Defied: Whenever depression threatens, Carol remembers all the cases she closed successfully.
 * Discussed: "Let me tell you right now -- I would rather have Det. Lime investigating my murder than any wet-behind-the-ears Wide-Eyed Idealist who thinks every criminal is always caught."
 * Conversed: "You know, for a character as cynical as Det. Lime, she seems to be awfully heroic."

The Knight in Sour Armor is over here, ya goof...why do I even bother sometimes (mutter mutter) ...