Bit of a lore drop here

Back when Gumbo had his symbol and was way more unhinged as a result, he brainwashed Gympie into falling madly in love with him and becoming his obsessed and devoted slave. Nowadays, since he no longer has his symbol and now has a moral compass, he secretly feels terrible about what he did to her, but he can't un-brainwash her because he doesn't have his symbol anymore and she's too obsessed with him for him to get her off his tail