Kyon is the first character to engage with her in a serious conversation. From this encounter, she gradually begins to soften up to others and starts to open up with her classmates. Later on, Haruhi took Kyon against his will and forced him to help her start the SOS Brigade, thus she has taken an unknown interests to Kyon later in the series. It is hinted that one of the reasons as to why Haruhi opened up to Kyon was that he resembled John Smith; John Smith and Kyon are the same person.
She is noted as smart, athletic, and naturally talented in any extra-curricular activities. She once joined every activity club in her school and quit because she found them boring, despite pleas by the club members for her membership. Her musical talent was highlighted when she stood in as the emergency lead singer and guitarist, along with Yuki, for the band ENOZ during the school festival.
Haruhi also has a very competitive personality and accepts without hesitation any challenge that crosses her, regardless of difficulty or time constraint. Her constant optimism and over-confidence make her seem arrogant. She has very high standards and won’t accept anything less than perfection from herself and her Brigade. She places a lot of trust in her Brigade members, especially Kyon, to get the task done whatever it may be. This can sometimes make her seem selfish and unkind.
She is not shy and often attracts a lot of attention to the point of not minding changing clothes in front of various people, more so when her SOS Brigade is in mind. When it comes to Mikuru she is very physically playful. She often comments on Mikuru’s attractiveness and seems to find a kind of enjoyment in exploiting it to her own ends, often through forcing Mikuru into and out of various costumes such as a bunny girl costume as if she were a human dress-up doll.
The SOS Brigade is very precious to her and has stated to Kyon that she has no intention of yielding her position as Chief to anyone else. She will go to any lengths, even by exploiting the members, to bring attention and support for her Brigade such as procuring room and materials, maintaining their website, participating in sports tournaments, organizing activities such as city-wide searches for strange phenomenon among other things. She wrote, produced, and directed the Brigade’s amateur-movie The Adventures of Mikuru Asahina for the school festival.
Her childhood is cited as an originator for her interests in strange phenomena. While attending a baseball game with her family, she was shocked to see the vast number of people who had come to see the game. Before then, she had often thought of herself and her life as being special and interesting, yet then came to realize that they were just ordinary normal occurrences and habits and that she is just one of many living human in all of Japan in which Japan is just part of Earth. Consequently, she believed then that there must be at least one person in the world who is living an interesting and truly unique life and sought out to effectively be that person thus motivating her to seek out the extraordinary.
After this realization she became notorious in middle school for doing odd things which included painting strange hieroglyphs all over the school grounds using a field marker and placing all the school desks in the halls. Additionally, she accepted and rejected every guy who had ever asked her out, the longest lasting a week and the shortest being five minutes. She only seeks relationships with aliens, espers, and time travelers. This shows the depth of her interest in finding non-humans and strange phenomena.
In actuality, Haruhi is believed to be either a crack in the space-time continuum, the first technological singularity to be spontaneously born in the universe, or some sort of deity, depending on point of view. This belief stems from a massive spontaneous universal event that occurred three years prior to Haruhi meeting Kyon, of which Haruhi is said to be the cause. The event attracted the attention of three prominent groups: the Extraterrestrial Integrated Data Entity, time travelers from a distant future, and a group of espers known as the “Agency.”
Her powers which are capable of altering, creating, or destroying reality are triggered by her emotions and inner desires. It’s been theorized by the espers that the current universe may be just one in a string that Haruhi had subconsciously created. In order to relieve stress whenever she becomes too emotionally unstable, patches of alternate dimension referred to as “closed space” are created and within resides gigantic blue entities that destroy the surrounding area. Despite having these powers Haruhi is completely oblivious to them or the existence of aliens, time travelers, and espers.
Haruhi also seems to hate showing signs of vulnerability to others. Following her concert performance at the school’s culture festival when she and Yuki filled in for two members of the band ENOZ, Haruhi showed awkwardness toward the band members when they thanked her the following day. As Kyon pointed out, Haruhi was not used to receiving praise from others because of how mischievous she regularly acts toward others because of her abnormal interests.
Though many of Haruhi’s efforts are devoted to finding supernatural beings, she does not actually believe in them. This is suggested by Itsuki during the first light novel, that Haruhi does not force himself, Yuki, or Mikuru to reveal themselves because her commonsense will not let her believe that they exist. In fact, between the first and second light novels, when Kyon tries to convince Haruhi that the other SOS Brigade members are more than they appear, she does not believe him. Later, she bases The Adventures of Mikuru Asahina on Kyon’s story.
However, unbeknownst to her is the true purpose of the SOS Brigade: to prevent Haruhi from becoming bored, as her boredom would bring about the end of the world as the SOS Brigade’s members know it. Kyon also happens to be a very important person in her life. For whatever reason, Haruhi “chose” Kyon. This is first said by Yuki, then restated by Mikuru, and Itsuki as well. She often relies on and trusts Kyon with anything. Kyon is the only person whom she has been open with, and when she briefly created a “new world,” he was the only person she had brought over from the “old world.” These are all made evident in the fourth novel The Vanishment of Haruhi Suzumiya, where she remained at Kyon’s side for the three days he was in a coma due to a small accident; however, he is apparently worth far more to her than even she realizes. Unknown to her, the person she knew as John Smith, who “helped” her draw weird symbols at the schoolyard of East Junior High (her old school) at night on Tanabata three years prior, is in fact, Kyon from the present time, sent back in time. Furthermore, his time there unintentionally created an alternate timeline where no SOS Brigade existed, Yuki, Mikuru, Ryoko, Itsuki, and Haruhi were normal humans and the latter two never transferred to North High, thus no SOS Brigade. Only by going back to that night again was Kyon able to set things right. Finally, should Kyon reveal to Haruhi that he is John Smith, it would radically change everything, as he stated to the Integrated Data Entity through Yuki.