She is his sun; she guides him with her plans, pulls him along with her words, and he's loyal to her.
He'd gladly be her moon, depend on her, and work with her, just some days, it's hard to be a moon, hard to know that all of Paris adores her, and yet he's her shadow. He doesn't hate it, not really.
Cat Noir will just mold to her guidance and yet when he finds his sun hurting him, he'll let her go and trust that she'll come around.
She doesn't need bright colors to become his sun, her bright red suit is enough of an indication. Heat follows red like a shadow of the color, and he knows that he can trust his sun even if they stumble or fall together. His sun will guide him, come up with quick plans to get them both out safe and heal any wounds that cling to them tighter than their suits.
His sun was never a quitter, even though she always needed the steady support of her moon to keep going.
He is her sun, from the bright yellow of his hair, to everything. His fame clings to him, his kindness perches itself on his shoulder.
Suns guide with a gentle hand, and she'd follow his lead into places darker than his brightness if he ever needed her support in them.
Marinette will be a moon as sturdy as that can be; she has moments though when flickers of being a sun peek through, but not enough to overshadow him.
She'll follow him no matter what she's wearing, she'll follow him into the theater with a towel on her head and still in her pajamas. It's what a moon would do, be loyal, be supportive even when times are hard or even when they need to slip into secrecy.
Adrien is her sun, and she'll gladly follow as his loyal moon even if the rest of the world thinks its nuts. Her love for him will remain as steady and strong as the love the moon has for the sun since neither can ever be as strong or as loved without the other's support, without the other's presence.