One of the central ironies of Piranesi's character is his generosity, which at times borders on naivety. Take, for example, his rationalization of the Other's mysterious access to a wide range of goods:
That being said, it occurs to me to wonder why it is that the House gives a greater variety of objects to the Other than to me, providing him with sleeping bags, shoes, plastic bowls, cheese sandwiches, notebooks, slices of Christmas cake etc., etc., whereas me it mostly gives fish. I think perhaps it is because the Other is not as skilled in taking care of himself as I am. He does not know how to fish.
During Sorensen's visit, Dr. Ketterley performs a ritual that he says will transport the two of them to the House. Sorensen's lighthearted reaction to the ritual proves bitterly ironic:
Unlock with LitCharts A+‘You need to focus on the candle,’ [Dr. Ketterley] said.
So I did.
But at the same time, I was thinking about that pale square in the dark patch and the candlestick fitting into it. And that was the point at which I realised that he was lying. The candle had stood in that precise spot many, many times and he had performed this ritual over and over again. He still believed. He still thought he could reach the other world.
I wasn’t afraid, only incredulous and amused.