Two "let's calm down"

The smaller one. Its shell is lighter, almost caramel-colored, and shines more because it's always licking itself to stay clean. It has a darker, round spot on its back, as if someone had stamped it with a quality seal.
His eyes are large, round, and a sweet, warm brown, with long eyelashes that give him a perpetually tender expression. He's snuggled up to his brother, his tail curled and his tongue sticking out, smiling as if the whole world were a game.
Personality: Pure sunshine. He's innocent, playful, and a little clumsy. He's always happy, even in an abandoned box. He's the kind of boy who would go "squii~!" with excitement if he saw a leaf moving in the wind. He trusts his older brother blindly and follows him everywhere (even though he sometimes trips and rolls around inside the box).

The eldest (the one who was born just a few minutes earlier):
Its shell is a slightly darker, warmer brown, like milk chocolate. It has a small, lightning-shaped crack on the right edge, a birthmark that makes it unique.
His eyes are intense red, almost maroon, and he always looks at everything with a mixture of curiosity and distrust. He's the most alert: his head is raised, his front paws resting on the edge of the box as if he were ready to jump out and defend his brother at any moment.
Personality: Serious, protective, and a bit grumpy. He's the typical older brother who sighs deeply before doing anything. If he could talk, his first sentence would be something like, "So, what do we do now, genius?" He likes to be in control (even though he's a baby and can't control anything).