Lelouch and Suzaku
These two boys are child-hood friends. They met when they were 10, when Britannia's Emperor shipped off Lelouch and Nunnally to Japan.
Lelouch and Suzaku are true friends. They have different views and different personalities, and yet together they work so well and get a long fine. Together they can do anything, with Lelouch's intellect, Suzaku's athletic ability and the trust and understanding they have in each other, they are unstoppable.
They weren't always friends though, their first meeting was rocky. As seen in the first picture drama, Lelouch and Suzaku fought with words and fists when they first met. Suzaku viewed Britannians, or the derogatory term he uses, "Buriki", with contempt and prejudice. He immediately disliked the Britannian boy who came and started living in his home. Lelouch, didn't like the boys attitude or politics, and getting beaten up by him obviously didn't help. In short, Lelouch despised the Japanese for using him and Nunnally as political tools. Suzaku, despised the Britannians as his father had taught him.
While at the Kururugi Temple, the two didn't talk for at least half a month. However, Suzaku saw the way Lelouch lived, and became confused with the prince. In Stage 0.515: The Invited Prince, Suzaku is bemused. He watches as royalty of the most powerful empire in the world has become so desperately independent. Lelouch tells him, that he is living with his own strength. This makes Suzaku think- he finds it an odd statement, that living is just so natural. He felt ashamed but he wasn't sure why. Lelouch was living in his old, rundown play house, and was getting beaten up everytime he went to town to buy groceries.
Lelouch also became bewildered with Suzaku. In Stage 0.521: The Vanished Nunnally, Suzauk offers to help search for Nunnally. Lelouch tells him that he needn't to, that his father, Kururugi Genbu, would be angry at Suzaku for helping a Buriki. Lelouch sees no sense in a Japanese like Suzaku, interfering or helping a Britannian like himself. Suzaku becomes angry and tells him that he'll do what he wants to, and that the fact that he's Japanese and Lelouch and Nunnally are Britannian have nothing to do with it. Suzaku's brash, honest and boldness are illogical to Lelouch. Lelouch doesn't see any benefit for Suzaku, so he doesn't see why Suzaku bothers.
Through these few interactions at children, I belive this is where Suzaku starts apreciating things more. He becomes less spoilt, and starts to appreciate life more when he sees Lelouch struggle so hard to live. Suzaku learns the deep meaning of life form Lelouch. Lelouch also learns from Suzaku. Lelouch is a completlely logical person. Don't do something unless you gain something from it, don't do something if there are consequences for it. Suzaku brings something into the equation; do something if you want to do it.
Lelouch and Suzaku are polar opposites. But through that they learn from each other.