Basic Trope: A (usually) female character who conceals a sweet side with a cranky exterior, or conceals a cranky side with a sweet exterior. Most often occurs in UST situations.
Straight: Summer loves Danny, the school's resident daredevil. Unfortunately, his antics frequently get on her nerves, and she lets him know it. "Danny, you jerk!" Summer also probably denies any romantic feelings for Danny. "How could I like that idiot?"
Downplayed: Summer gets annoyed with Danny a little faster than she does with other people. You have to watch closely to notice it, though. When asked if she has feelings for him, she laughs and denies it.
Summer's best friend, Shrinking Violet Alice, also really likes Danny, so Summer feels she can't act on her love for him. Danny, being clueless, constantly acts in ways that are hurtful to both Summer and Alice, causing Summer to lash out at Danny in frustration.
Summer doesn't want to be in love with Danny, be it his appearance, his interests, etc.; but is, and is desperately trying not to be. The stress causes her to insult him.
Summer has been hurt before, and has sworn off romance, but can't help being attracted to Danny. She tries to suppress the feeling by focusing on his negative traits and insulting him.
Summer has a Jerkass Fašade to keep up, and acting rude to Danny is part of it.
Summer is suffering from a Cartwright Curse, and tries to drive Danny away because she doesn't want anything to happen to him.
Summer is bipolar or has a personality disorder (either borderline or dissociative), which explains why she hates and loves Danny at the same time.
Summer and Danny were in a relationship in the past, and it ended badly. Summer is still attracted to Danny, but pulls away whenever it looks like they might be getting too close to each other, since she hasn't forgotten why their previous relationship failed.
Summer is The Mole and knows better than to sleep with the enemy. So she denies any feelings she might have for Danny.
Summer is eight years old and has her first crush, but she still thinks boys are gross.
Danny reminds Summer of her favourite cousin, who was also a daredevil and who died years ago in a motorcycle accident. She'll never admit this out loud, though, and expresses her concern by be(r)ating Danny every time he does something stupid. (Which is often.)
Summer does have a crush on Danny, but rather than admit it to him (for whatever reason: past heartbreak, fear of being friendzoned, possibly hiding her true sexuality), she approaches him as a friend and just wants to be his friend. Unfortunately, that doesn't stop Danny's (or even Summer's) friends from calling her out on it, which pisses her off and leads her to go after anyone who mentions it.
Summer seems to like Danny, but it's later revealed that she never did like him.
Summer and Danny are actually sister and brother, and Summer only berates Danny of his foolishness because she has to as a parental substitute for whatever reason. Otherwise, she would rather not exhibit this perceived mood swing.
When Danny reveals his love for her, Summer instantly reveals that the feeling is mutual.
Danny reveals that he has a crush on Summer, Summer feels like crap for yelling at her and his friends, and learns to accept it.
Danny (for whatever reason) makes her feel less broken but every time she gets comfortable fear snaps her into more aggression.
Parodied: Summer bakes a birthday cake for Danny, with strawberries arranged in the shape of a heart. When Danny notices the heart and comments on it, she hastily claims it was a badly misshapen triangle. Later, she admits that it was a heart... then takes it back. Still later, she takes back the taking-back, which leaves Danny hopelessly confused and Summer no closer to expressing her true feelings.
"Maybe he doesn't seem that into you because he thinks you're bipolar? ...Please put the hammer down, I was just joking..."
Invoked: Summer yanks Danny out of the mess he's gotten himself into this time... and verbally berates him before, during, and after. Little does she realize that Danny does this because he thinks Summer is cute when she's angry.
1. Summer's disorder makes her violent on occasion but Danny's willingness to be her friend regardless inspires her to take medication in addition to a concentrated effort to reign in her more violent tendencies. She regularly thanks him for his support.
2. Whenever Danny can no longer stand Summer's crankiness, he calls her on it. This makes her apolgoize tearfully and do her best to make it up to him. Danny forgives her and there is peace for awhile until the crankiness comes back. Their friends call this 'the tsundere cycle'.
4. Danny, in order to end the bad blood, goes up to Summer and asks what he did to piss her off. She stares at him like he's an idiot. "What's it going to take to get it through your thick skull?" She pauses for a Luminescent Blush and looks away, "Don't you get it? I love you, dumbass!"
5. Summer and Danny are Vitriolic Best Buds who enjoy the bitterness. When they're calling each other harsh names or rough-housing their friends say they are flirting.
6. Summer does nice things for Danny (such as making him lunch or helping him study) so he will believe her when she confesses. She still does bully-ish things but in a playful manner.
Summer decides to go through anger management to improve herself, and in the end goes from a Type A to a Type B.
Plotted A Good Waste: The writers make Summer a Tsundere so it will make more sense that nobody finds out about the Secret Relationship, or to make it more obvious.
Played For Laughs:
Summer is being a bitch towards Danny in public, but when she goes home, she pulls out a photo of Danny and gushes over him and kisses his face.
Summer constantly bitches Danny out everyday whenever he tries to approach her. She has a good reason to, due to her Abusive Parents constantly treating her like garbage and thus stunting her from expressing affection.
Summer's constant verbal and physical abuse starts having a gradual effect on Danny, making him feel depressed and unwanted to the point where he believes that Summer legitimately hates him. When she finally confesses her true feelings, Danny rejects her, flat-out saying he doesn't want to be in a relationship with someone who he thinks has nothing but bile and contempt for him. Summer, realizing what she was doing, tries her best to make up for the damage.
Are you quite finished playing with this trope, idiot? Back to Tsundere, you. ... Please? I-I'd really like that.