>>4384076She doubtlessly feels pain, as shown multiple times from start to finish. This indicates Rei has a functional physiological and neurological system to at least some extent; but it should also be noted that Rei obviously has a very strong capability to *endure* pain, far beyond what would bring even the strongest men to a state of disabled begging. She consumes food and seems to enjoy it more than as simple sustenance, so we can assume that many of the normal processes of a Homo sapiens sapiens are present. She clearly, though, has capacities alien to us, both in the light scan we saw near the beginning of the series as well as the extraordinary abilities demonstrated to us at the end, both before and after Instrumentality is instated. So at least until the end of 'Rei II', I think we could reasonably say that Rei feels heat or its absence. After, though?
