Kuudere/Playing With

Basic Trope: A (usually) Emotionless Girl likes a guy, but for one reason or another, hides her feelings under a cold exterior.

Straight: Keiko is rather quiet and cold. Her schoolwork is more important to her than love, but then she notices Sam...
Exaggerated: Keiko is emotionally distant with everyone, including her family, friends, and pup py. However, at first sight of Sam, turns into a gooey mess of affection.
Justified: Keiko transferred to a new school and feels like she's Surrounded by Idiots. Sam is a Snark Knight and helps her feel less lonely.
- Keiko has been burned badly by someone she trusted and is slow to trust. Sam manages to gain her trust, and she warms up to him as a result.
Inverted: Sam is a Jerk with a Heart of Gold, and causes the usually cheerful Keiko to give him the cold shoulder.
- Keiko is normally a loving person until she notices Sam and suddenly becomes emotionless when he's around her.
Subverted: Sam seems to be making Keiko warm up a little bit, but she's still aloof, and a relationship never happens.
Double Subverted: ...until the summer.
Parodied: Sam turns Keiko into a Clingy Jealous Girl over the weekend.
Deconstructed: Keiko has had trouble with getting close to people her whole life. Even if Sam gets on her nerves sometimes, she feels more comfortable with him than anyone else.
Reconstructed: Keiko has something of a misanthropic streak. Sam helps her realize that not all humans are bastards.
Zig Zagged: Keiko doesn't like Sam. Later, however, she seems to develop feelings for him, but then it turns out that she was just using him for her own ends. And then it turns out that even though it looks like that was what happened, she really did like him. And then it turns out that he was trying to manipulate her. And then it turns out that neither of them have actual feelings for each other. Until suddenly they do.
Averted: Keiko intimidates Sam and he never approaches her. She never notices.
Enforced: The writers want to give Keiko a Love Interest, but she reacts to them this way.
Lampshaded: "That girl doesn't seem to like anyone, does she?" "Well, I think she likes Sam. You see that sort of thing all the time in movies."
Invoked: Sam notices that, while Keiko is cold, he could try to warm her up to the idea of a Love Interest, and decides to go about winning her that way.
Defied: Keiko, meanwhile notices Sam's efforts and decides to ignore him.
Discussed: "Unlike what you see in movies, Sam, I am not interested. Please stop hugging me."
Conversed: "Oh, I see what's happening here. She's going to act all cold like she's not interested, but she is, and they live Happily Ever After."
Played For Laughs: Keiko is The Comically Serious in Sam's zany schemes.
Played For Drama: Keiko was going through depression, but Sam helps her realize she has much to live for and people who love her.

Go ahead and go back to Kuudere. I don't care. Really...I don't. (sigh)