Hannibal and Will’s first conversation is interesting because Will is defensive. I mean, Will is defensive towards everybody, but this time he finds someone who is as unrelenting as himself. We start with “Do you have trouble with taste?” And “My thoughts are often not tasty.” This can be a lot of things; I personally see it as Will asserting his job (and hiding behind his job i.e. he’s taking away the personal touch of “tasteless” which started this whole thing) and also as a joke because of how it’s worded. Then we get into the meat of it: “Nor mine. No effective barriers.” Hannibal implies he is the same as Will; his thoughts aren’t tasteful (given that he’s a therapist), and those thoughts bleed into other normal, day-to-day thoughts. This can or can’t be true. We don’t know. But for sure he is prodding at Will with a stick, and Will retaliates. “Well, I build forts.” Basically saying, ‘I don’t have that issue because I can segregate my thoughts well'—forts are stone and concrete; hard to conquer, so he’s presenting this image of 'I’ve got a concrete mind and I’m organized’. Hannibal challenges this, “Associations come quickly.” I like to think it’s because Will’s mind works so fluidly and quickly, it’s natural for him to not actively think about things; they just come to him. Hannibal is saying, 'When do you get the time to build forts when the associations are quicker?’ and Will, sore loser, goes, “So do forts.” That is, 'I’m so good at having a mind, I’ve got everything under control and you don’t even know’ which is a pompous lie of course. Finally we reach the breaking point, “No forts in the bone arena of your skull for the things you love.” Which is the equivalent of saying 'Hey I saw you stealing your neighbour’s underwear’ because Hannibal’s got him. And the way he says it too. Agreeing with Will in his analogy of forts being concrete; associating it with the skull (which is, of course, made of bone and is hard and grey like concrete) but saying that is the only thing concrete in your head. No forts. Just rivers of thoughts flowing into the ocean where they all mix without individuality. Will can’t protect his precious things from the violent things he sees, they all mingle together. He looks at clear water and sees red. He sleeps in his own bed next to dead bodies. And it’s like Hannibal has stripped Will of his face and flesh and shone a flashlight right into the back of his skull through his empty eyesockets going “Hm. Interesting.” And that’s why Will gets so pissed and leaves.