Spring was Eriol's favorite season.
When he was reincarnated as Hiiragizawa Eriol, and when he knew he was no longer Clow Reed, he chose his birthday to be March 23. Although his other self, Kinomoto Fujitaka, who had no memories of his life as Clow Reed, had his birthday in January 3, Eriol wanted his to be in spring.
It was believed that Clow had died during winter, symbolic of the old coming to an end. Spring was symbolic for a new beginning, a new life. He loved all the colors and life that spring brought with it; it reminded him of good things. Things he hoped he would achieve in this life.
He figured that if he was going to enjoy this life like he was not able to in his past one, he might as well have something to remind him of the good things to come. Family, friends, school, love, every day situations.
And so far, he truly was enjoying this life.
Author's note: Happy birthday Eriol!
Disclaimer: I do not own CCS