Isolation has a few noticeable effects on a captive. They become grateful for any interaction they can get. For Sister Dee she sees the paltry meal she is given as a gift from PD. She is happy to have it, even though she knows that later on she will have to pay for it.
Those kinds of delusions are hard to maintain once PD has pulled her out of the hole. He has no interest in freeing her or making her time any easier. He wants to hear her scream and sob. Her tits are the best place to start. They are clamped down by a cold iron bar and it makes them stand out perfectly for torment.