He has about ten times the hours that I have and single-pilot IFR is his bread-and-butter. Part of a team, he ain't!
Over the years we have come to a very workable arrangement of who does what when he's PIC.............I am expected to look after the charts, plates, times and fuel state. When the autopilot is flying we both keep an eye on the gauges and position. If the autopilot breaks then I am expected to take my turn at straight-and-level. He is comfortable enough to grab forty winks and leave me "in charge". In an emergency I grab the book, find the pages needed and read the right bits aloud - he flies.
If I am PIC (generally only when flying my own aircraft) he tries to sit back and shut up. Until recently I didn't have an intercom, so I could just unplug him and get on with it!