Trump from day one was advised by his attorneys to fully cooperate with the Muller investigation.

The real relationship between Mueller and Pres. Trump is exactly the same relationship between the lioness and the antelope. Mueller is there to bring down and devour Pres. Trump! The lioness role in the hunt is to bring down and devour the antelope, but at least the antelope runs instead of cooperating with the lioness and laying down making it easy for the lioness to rip open the belly of the antelope and devour the antelope.
However, Pres. Trump’s attorneys advise Trump to do just the opposite of what he should naturally do which is to fight Mueller with every right he has as a president and a private citizen short of firing Mueller.