Reading Liang Shuo's latest contribution to the Chronicles of the Three Kingdoms thread got me thinking a lot about Sun Quan and Zhang Zhao's personal and working relationship. It really seemed like, beyond all of his other loyal vassals, Sun Quan was particularly harsh on Zhang Zhao.
Take, for instance, his coronation as emperor. He praised the talents of Zhou Yu, and as Zhang Zhao was about to nod in agreement, added, "but had I listened to the words of Zhang Zhao, I would be in a ditch right now." It seems a bit needless ot make a comment such as that at a celebratory event, especially when Zhang Zhao was hardly the only one suggesting that Sun Quan side with Cao Cao at the time.
Then, Zhang Zhao gave honest advice to Sun Quan against allying with Gongsun Yuan, and Sun Quan grew needlessly vexed at him and threatened him. Then, when Zhang Zhao left the court, Sun Quan's treatment of him only grew more bizarre: piling dirt outside his door.
It's evident that there was a great deal of conflict between the two, though Zhang Zhao's loyalty cannot even be questioned. Certain sources mention that, when Sun Ce was on his deathbed, Zhang Zhao strongly urged him to appoint Sun Yi as his heir rather than Sun Quan, but some historians, including Dr. Rafe de Crespigny, have discounted this. Regardless, I think this event did actually occur and may have been the start of the conflict between the two - Sun Quan held a grudge against Zhang Zhao for favoring the talents of Sun Yi over his own, and though Zhang Zhao gave his all in service to the state, Sun Quan never forgave him.
"There are those who try to shape the world to their own whim,
and then there are those who allow the world to shape them.
It is in the balance that greatness is achieved."