Steve is defensive especially now that Don has pointed out that nobody knows what he has been doing in the basement. The evidence suggests that Steve is going to get angry at Steve for accusing him of causing all of the strange goings on in the neighborhood. To Don, this anger is more evidence that Steve is up to something.
acclimatization (short-term physiologic responses to a stress)
acculturation (the process of assimilating new ideas into an existing cognitive structure)
By saying that they are genuinely happy for his return
Good deeds will be rewarded