Monster future!Jon in heat. Hiding in the tunnels, feeling both stripped bare vulnerable and like it has a hair-trigger temper. Needs to breed and be bred. Past!Jon looking for it, finding it, this huge beautiful monster and it’s so wet and so hard and its looking at him like it hasn’t decided how it wants to devour him. He’s terrified. He’s soaking wet. Gaze slipping between its piercing, staring eyes and it’s erect cock, swollen at the base where the knot will form. He could probably escape, if he backed away slowly. Let himself slip back into the darkness slowly and calmly. Instead he turns, and he runs.