Say what you will about the anime, but it did have its good points. One of these was a small moment in episode 9 where Kurumu offers to carry Yukari back to camp after she'd been injured. Yukari's okay thanks to her Healing Factor though, so she walks off by herself, leaving Kurumu to run after her and shout at her not to exert herself. She may not have gotten the depth she did in the manga, but she does care for her friends, and that's certainly something.
Manga: Season I
T'was the week before Tsukune's 16th birthday. He was hoping to spend it with Moka. She, on the other hand, was spending the week modeling for an art class. As the days pass by and Tsukune keeps missing chances of asking her to be with him, he grows increasingly frustrated and ends up almost dying (again). He wakes up in a hospital bed on the day of his birthday, thinking Moka had forgotten it and feeling quite down. And then Moka proudly reveals the drawing she'd spent the past week on. The theme was "something important to you". The drawing is of Tsukune. And to top it off she tells him she loves him.
Chapter 26. Moka has been having doubts, avoiding the others, and thinking about leaving the school. Kurumu takes her somewhere to meet in private after some not-so-subtle threats from Kiria. There, first she tries to remove Moka's rosary herself, concerned about her running into Kiria. When that fails, she expresses her frustration over how Moka is acting and tells her to leave. As Moka walks away in tears, Kiria shows up and chastises Kurumu for driving her away from him. He then sics a pair of cyclopses on Moka to try and draw out her vampire side. He holds back Kurumu, hinting at how this will leave Tsukune open for her. She stands there a moment looking at Moka, then turns her head away. Then, just as one of the cyclopses has Moka cornered, jumps in to slice him in the face. She calls out Kiria on his enjoyment over the whole thing and says her heart won't change so easily. Then, Moka stands up, ignoring Kurumu's order to run, and stands with her to fight. They exchange a few comments about sticking together, smile, and then proceed to kick ass.
During the school festival both Mizore and Kurumu had told their mothers that Tsukune is their boyfriend. He was set to have lunch with both families, neither of which knew of the other one. All he wanted to do was walk around with Moka. The heartwarming came from Mizore who, upon realizing what Tsukune's wish was, made ice clones of him and sent them to meet the mothers, while the real Tsukune went with Moka.
Chapter 34 of season 1. After everything that Hokuto has done, Tsukune still believes that Hokuto's wish to make the school peaceful was genuine. It's enough to move Hokuto to help sabotage his own plan.
That is however, slightly spoiled with recent events which imply a Kira-esque plot on Hokuto's part.
* Gasp* No one has mentioned the scene in season 2 of the manga where Mizore tries to commit suicide by jumping out of some odd-story-high castle window after being essential sold off into an arranaged marriage and Kurumu flies out of the window after her. As Mizore weeps as she felt violated by her new 'husband', who had kissed her against her wiil, Kurumu cuts her off by kissing her, tearfully asking "A kiss isn't so bad, is it?" all the while drifting down to earth. Sure, Kurumu threw in some tongue but considering their frenemy status, very awww-inducing indeed.
Easily Kurumu's Crowning Moment of Awesome and massive Tear Jerker, all rolled into one spectacular scene. The normally emotionally-restrained Mizore is absolutely hysterical screaming "He touched me everywhere, I didn't have time to resist. Scared... I was so scared!" about her near-rape. (The only thing he did not do was physically rape her.) Mizore thinks that she is ruined forever, when Kurumu kisses her, she does absolutely the one thing to convince her that yes, someone will want to kiss her again. At which point Mizori breaks down entirely, crying like a baby in Kurumu's arms, who holds her and tells her everything is ok now.
And as for the tongue part, Kurumu is a succubus after all; it probably comes naturally.
The scene where Sun's adoptive human mother is able to look past her hatred and prejudice. Sun is found to be a siren, and a siren killed the woman's husband, but she embraces Sun and reassures her that she is her daughter.
 Make sure no one else can hear your AWWWWWWWWW!
In Inner-Moka's spotlight chapter in which she decides to go to school for a day, she ends up becoming depressed when she realizes that she is a Lethal Chef. Initially the story implies it to be a Break the Haughty moment, but then it's revealed that she's actually depressed because she wanted to cook something to impress Tsukune. Despite the fact that her food looked horrible, Tsukune ate it anyway and complimented her on how good it was regardless. Her reaction? Just look at the picture on Defrosting Ice Queen.
Ling-Ling's farewell speech to her younger brother before trying to take down Akuha
Also, "I'll fight. There's no way I'll let him lay another hand on anyone!"
Chapter 48 of season 2 features Yukari's heartwarming statements to Fong-Fong.
A subtle one in chapter 33. Akasha tells Alucard that she won't permit him to take away her beloved daughters. Plural. Right after Akuha attempted to kill her.
Chapter 53, when Kurumu reflects on her friendship with Moka.
In truth, there were so many times when I thought, "If only I could hate you." If only I could hate you. If only I could hate you. I thought that so many, many times... It's strange, isn't it? I'd thought that living for love was everything to me, and yet...
↑Fridge Brilliance: when she turned her head, she was looking at Kiria and seeing his expression