thetis is a figure in greek mythology, often appearing as a water nymph or a goddess of water! she tries to make her son achilles immortal by dipping him in the river styx as a baby, but holds onto him by his heel. his heel, being untouched by the river, is his weakness. i used the line "thetis held my gut" in a poem to say that the narrator's gut is their weakness, with a weak gut symbolising anxiety and emotional weakness (+ whatever else the reader chooses to interpret!). the line has stuck with me ever since so i thought id put it in my bio on here :))
(sorry for this super long, english teacher ass answer, i j loved this line when i wrote it and am actually thrilled to get to talk about it 😭😭)