17:22,23
Jesus reminds them yet again that He is going to suffer, be killed and then rise again. Since He has shown them His glory He is emphasising the cross all the more. Note that although He has mentioned His death and resurrection, it is His death that seems to be what His disciples are focused on. The concept of resurrection meant nothing to them, but death did, so they were filled with grief.
17:24-27
The mundane realities of life continue to hit them. Now they are asked for the temple tax. Peter tells Jesus what happened. Jesus replies that it is ridiculous for the children of the king to be asked for taxes. Even so, Jesus pays the tax, using miraculous means, with the money being supplied by a fish. So they are aware of the true situation and status, but also not causing unnecessary offence.