A false peace on the moon

Athrun and Kira meet in Copernicus, a city on the moon, when they were roughly six years old. One way or another, they become close friends and Athrun becomes the bossy and dominate one, often helping Kira with school work and such, and Kira being the cry baby. Their relationship can be heard in the Suit Drama CDs in vol.1 STRIKE x KIRA YAMATO and vol.2 ATHRUN x CAGALLI.

Athrun was particularly good with robotics and micro units, so when he found out Kira had signed up for a really difficult assignment to build a moving robotic animal, he builds it for Kira before he had to leave for PLANTs, and gives it to Kira as a farewell present when they were both roughly thirteen. Kira treasures it from that point on, and he is rarely seen without the company of Torii, the green robotic bird Athrun built for him.

When Athrun leaves to PLANTs, he was hoping Kira would soon follow, so that they could be reunited later on. Never could he have imagined Kira would join the Earth Alliance and have to fight him. Kira, for his part, was shocked Athrun would become a soldier, recalling Athrun had hated war, but the death of Athrun's mother in Bloody Valentine had changed all that. One of my favorite scenes in Gundam SEED is at the end of episode one, when Kira and Athrun come face to face, their emotions and the shock they must feel always move me everytime I rewatch the series.