Grésillent comes from the verb grésiller, which describes a light crackling or sizzling sound, like a gentle fire or static electricity. It's a very sensory and somewhat rare word that paints a vivid sonic picture.
In the song, the singer says "Je n'aime que tes bas résilles / Qui dans mes pensées grésillent" (I only love your fishnet stockings / Which crackle in my thoughts). This creates a strange and captivating image: the stockings generate a kind of electric, sizzling static in his mind, suggesting an obsessive and almost physically charged desire that haunts his thoughts.
This song is a dreamy, synth-pop duet about a completely obsessive, all-consuming love. The two singers trade verses, building a world where their romance is the only thing that matters. He sees her everywhere, telling her, "Je te cherche dans mes songes / Je te traque dans mes rêves" (I look for you in my daydreams / I track you in my dreams), and feels powerful only with her, declaring, "Avec toi je suis roi" (With you I am king).
She feels the same way, admitting that when she wakes up at night, "Je suis seule sous mes vices" (I am alone under my vices), but her love for him is a constant. The chorus is their shared, simple plea: "Aime moi dans la neige / Aime moi sous le soleil" (Love me in the snow / Love me under the sun). They want to be loved in every season and every moment. It's a perfect soundtrack for feeling like you and someone else are the main characters in your own romantic movie.