no heart is the same as another
For a long time, Yuki, the Rat among the zodiac spirits, has felt inferior to Kyo, the Cat — their rivalry and mutual animosity is something that is brought up in the first volume and pursued throughout the series, subtly developing along the way as the two of them mature as individuals. The Cat is treated as an outcast among the Sohmas, the story behind the zodiac not allowing the Cat to be acknowledged as one of theirs.
Despite that, Kyo manages to make friends easily and naturally, whether among the younger zodiac characters or at school — something that Yuki admires, but can’t bring himself to admit out loud. Yuki, in contrast, has a difficult time opening up to people and getting close to them, which makes it seem as though he intentionally keeps others at a distance. This difficulty is furthered by a traumatic experience in the past as well as the way his fellow students revere him as the “school prince”.
When Yuki confides in Tohru about his feelings of inferiority and she brings up all the girls who adore him at school, he tells her that he’s only kind to them because he wants them to like him. “It’s not the same. I merely buy their friendship. Being kind to others for your own selfish reasons isn’t really kindness at all — it’s pure hypocrisy.”
Tohru doesn’t respond right away, but later on, when Yuki tells her that she has a good heart, she mentions in passing (while being overjoyed) whether or not that is considered hypocrisy as well: “After all, I also want others to like me…”
Mother always said that it is better to trust than to doubt others, and that a good heart isn’t something you are born with. When we come into the world, we only possess instincts that we need to survive, like hunger or greed. A good heart is part of the human body, and one has to nurture it for it to grow. That’s why no heart is the same as another. Tohru, Volume 1
Tohru assures Yuki that his kindness is just as genuine as anyone else’s, and describes its shape in her own words. She also responds positively to him confiding in her, as that trust is the foundation for a good friendship.
Each of us is born with desires. They are easy to recognize because they resemble each other. Kindness, however, exists in many shapes and colours… Often, we fail to see it or think of it as insincere and misunderstand it. But, Tohru… Anyone can mistrust others. It’s the easy thing to do. You have to learn to place your trust in others. I wish for you to never lose your trust in others. One day, this capacity will be of great support to someone. Kyoko, Volume 1
The emphasis in this scene is on Tohru being the one who reaches out to others and reassuring them, but behind Tohru is Kyoko and the respect Tohru has for Kyoko. Tohru may think and speak of Kyoko all the time, but she is also happy to share her mother’s words with everyone else — words that have stayed with her and shaped her as a person. This scene is only the first of many instances to come where Kyoko’s words, through Tohru, manage to be of help to someone else.
In Yuki’s case, who struggles with his own identity and feels like he doesn’t belong and isn’t good enough, the words that were passed down show him that it’s fine for him to be the way he is, and that each person is different. He may not be able to overcome his self-doubts right away, but at least he knows that there is one person who recognizes and acknowledges him as who he is.