The first thing you think of when you see her is her childlike nature and her sunny exposition, she finds beauty in everything and that is probably her major fuel to go on and always be happy. Which means that she easily bonds with people, and those who call her friend have an urge to protect her.
On the other side she shows her determination and how strong is the moment when someone hurts one of her friends or loved ones, that is the moment you see the fighter in her and that fire magic that she represents is not only because of her looks and sunny exposition, but because she is like that also in combat.
While after killing Zagato and Emeraude all three of them suffered, it is said that probably she suffered even more, because she is much more in touch with the emotion than anyone around, and this means she has more trouble to get over things, even if they were done because they had to be.
While it seems that sometimes she doesn't understand things, or better, she understand them in the simplest way there is, like for example love, she loves everyone, but if we go digging a little more, the fact that she is 14, and somehow in that department less mature - the truth is that she loves everyone the same.
Hikaru has the strongest hart and the strongest will in the group and around, probably only Eagle Vision along with Lantis could be on her level, but still she beats them - which means she becomes the pillar of Cephiro.
Another thing is that she is honorable, she fought Lafarga with honor, as she didn't used magic, because, hey, that was a swords match and even if she was weaker than him, she still refused using it to win. Code of honor of a samurai.
She is tomboyish, and she speaks like a boy. Fuu does ask her ones about it, and she answers, that well, she lived all her life with three older brothers.
Zodiac sign - Leo
Hikaru is Leo as zodiac sign, but the only negative trait for her personality from that side is that she is stubborn as hell and that it is - I don't see arrogance which is a trait I came to notice in lot of Leo's I know. Still the person who is my personal hero, my late grandmother, she was a Leo so female leos are awesome!
Leo's are known for their tenderness and going to all extents to help you, they are also born leaders, and that's why Hikaru lot of times is seen as the leader of the Knights, even if not well defined, she is the one that in the end takes the difficult decisions, and she is the one who became the pillar.
Leo also is a part of the astrological signs of fire, which is Hikaru's element - while their energy is contagious, we can see how she manages to lift the spirits of those around her, fire is also unpredictable, so Hikaru lot of times does things that people aren't able to predict - like taking Eagle back to Ceophiro from the Pillar test.
Hikaru as leo shows that she is courageous, influential, passionate and loyal.
Blood Type O
The Japanese culture and their obsession over the blood type. Like it said that the Zodiac sign shows personality traits, so does the blood type. In Japan the O blood type person is called THE WARRIOR. Again looking at the traits they say that a blood type O has; Hikaru mostly shows the positive parts - This kind of people are outgoing, expressive and passionate, also highly motivated and natural leaders. They have strong physical presence (Hikaru even if small she is strong) and aren't afraid of gamble, because they are convinced they will win. Aside that other traits for this blood type include the role of creating harmony around themselves, they are peaceful and carefree, big hearted, benevolent, outgoing, social, athletes and here I will stop because there are too much things that are said about this blood type.
The fact is that Hikaru is all those things that I listed, probably because of that the CLAMP choose this blood type for the girl, because it suited her. She represents the Blood Type O magnificaly, at least the good parts, as she is NOT arrogant or similar things.
I wasn't sure if I would write about nova, and decided to add her to the personality section, because even if she is a character in the anime, she is part of Hikaru's heart. Differently then in manga, Hikaru has more difficulties loving herself after the ordeal with Zagato and Emeraude.
Nova was created by Hikaru's self-hatred when they killed Emeraude, and searched for Hikaru, who was back home, vulnerable she got taken in by Debonair and used against Hikaru.
Nova hates what Hikaru loves, and loves what Hikaru hates. In the last episode,
when they confront each other, Hikaru tells Nova that she wishes to love herself
back and to love Nova, asking her to be again part of her heart, so that nor
Hikaru or Nova would ever felt alone anymore.