Myoujin Yahiko
At first glance, Yahiko may seem like nothing but a discourteous, rough, rude, and arrogant brat. He's a little bit of each, but that's not all he is. When Kaoru and Kenshin first came across him, he was working as a pickpocket for a syndicate. The orphaned son of a former samurai who had come upon hard times, Yahiko had very little choice, and he had to work for the syndicate to survive. He tried to pick Kenshin's pocket but was caught. Kenshin then tried to just give his wallet to Yahiko but Yahiko, being proud, threw the wallet back at him and stalked off angrily. Later on, Kenshin rescues him from the Yakuza. Yahiko joins them as a student in Kaoru's Kamiya Kasshin Dojo, most likely because Kenshin approved of the reason why he wanted to become stronger (to defend his parents' honor, rather than for the sake of being strong).
Despite his rather rude treatment of his master (Kaoru), Yahiko's a good kid at heart. He understood his father's sense of honor (which got him killed) and he understood how his mother sank to prostitution and eventually died to raise him. He could easily have become bitter, resentful, and angry with his parents. Instead, he grew to have honor and pride and respect for life. In many ways, he is like a small Kenshin, although not always so prudent.
Even though he yells at Kaoru all the time and is generally disrespectful, he can - and will - bow to his elders' wisdom when necessary, earning not only the trust and respect of Kaoru, but also - perhaps more importantly - Kenshin's. He won't stand for being patronized and treated like a child (even though he is only 10 years old), but makes up for it by acting as grown-up as he can. Yahiko's sense of pride won't let him be treated like a helpless kid or - even worse - a burden, baggage, that his friends have to protect and so he fights his own battles as much as he can. It is through these battles that Yahiko develops his natural aptitude for swordsmanship. He proves to be an exceptional student, absorbing all Kaoru has to teach him and more. He even managed to learn Hiten Mitsurugi just by watching!
Besides swordsmanship skills, however, Yahiko was also able to learn important life lessons from Kenshin, Kaoru, and Sanosuke, eventually becoming not just a good swordsman but also a good person. In the end, he becomes a curious (but nice) mixture of Kenshin, Kaoru, and Sanosuke. Perhaps it's because he grew up with friends who are not only great warriors but also good people that he becomes great himself. In fact, the desire to become like Kenshin is the major driving force in his life. Near the end of the manga, he selflessly risks his life to protect his town and succeeds in bringing a Kenshin who had given up on life back, when all the others had failed. It's kind of funny to think that, in a way, the fan "inspired" the object of his admiration.