Médisances is an elegant French word for "slander" or "malicious gossip". It's not just simple chatter; it specifically refers to speaking ill of someone, especially when they're not there.
In the song, ZAZ powerfully sings of being the victim "De cent médisances à mi-voix" (Of a hundred slanders in a whisper). This single word captures the pain of betrayal by those who pretend to be kind to her face, painting a vivid picture of the emotional struggle at the heart of the song.
This song is a conversation the singer is having with her own heart. She calls it crazy—"Mon cœur, mon cœur tu es fou" (My heart, my heart you are crazy)—for feeling so much. She's dealing with a recent heartbreak and the sting of betrayal from people she thought were friends. She describes them as being overly sweet to her face, "une bonté trop câline" (a too cuddly-kindness), while they "assassinate" her with gossip behind her back.
Even though her heart has been "Passé au fer de tant de haine" (Branded by so much hate), she refuses to be a victim. She suffers quietly, "Sans que je crie, sans qu'on me plaigne" (Without me screaming, without anyone pitying me). Instead of breaking, she finds a strange and powerful energy inside herself to keep going, which she calls "un feu farouche et doux" (a fierce and sweet fire). It's this wild, contradictory flame that fuels her through the pain and isolation.