To Kakashi, team 7 is like a paint palette.
Start with the primary colors, and you can get everything in-between.
Sasuke is blue. (The color his eyes are not.)
Sakura is red. (A pinker red, but one nonetheless.)
Naruto is yellow. (Golden like the sun.)
They fit together perfectly on the canvas.
Two years later, the paints have been mixed and smeared.
Sasuke is a dark purple. (Blue mixed with Orochimaru's black and Itachi's red eyes.)
Sakura is a dark green. (Red replaced with the mixture of blue and yellow, Sasuke and Naruto.)
Naruto is a dark orange. (Yellow mixed with Kyuubi's red and the black of Akatsuki cloaks.)
Kakashi picks up the palette and raises a brush to the canvas—
He is pleased to find the colors fit together perfectly.