Te Rau is an exquisite carver (with a particular fondness for pounamu, a local green stone that he prizes more than gold) and was a great friend of the late Crosbie Wells. He is also part of council of twelve men who meet at the Crown the night the book opens.
He's described as a pretty impressive dude, physically speaking:
Te Rau Tauwhare was not quite thirty years of age. He was handsomely muscular, and carried himself with assurance and the tightly wound energy of youth; though not openly prideful, he never showed that he was impressed or intimidated by any other man. (I.3.117)
Given his strength, you get the sense that you probably wouldn't want to get on Te Rau's bad side (Are you listening, Frank Carver?).
And don't go thinking that Te Rau is one of these people who doesn't know how fabulous he is—he definitely knows, even if he tries to keep that awareness on the down low:
He possessed a deeply private arrogance, a bedrock of self-certainty that needed neither proof nor explication—for although he had a warrior's reputation, and an honorable standing within his tribe, his self-conception had not been shaped by his achievements. He simply knew that his beauty and his strength were without compare; he simply knew that he was better than most other men. (I.3.117)
So, whereas a lot of people kind of look to others when calculating their own self-worth, Te Rau is totally confident in his own superiority to everyone else.
You'd think that this intense confidence would make Te Rau feel pretty good about things, but it actually stresses him out because he's afraid it might make him shallow. So on top of being confident, Te Rau is also reflective and tries to keep himself humble…we're just not sure how successful he is, given the special gifts and attributes nature seems to have given him. How can you possibly be humble when you think you're naturally better than everyone else? Gosh, it must be so hard to be perfect.
Even though Te Rau and Crosbie were BFFs, he inadvertently became responsible for Crosbie's death (we think) when he tells Frank Carver where to find him. Hey, as far as he knew, Carver was an old friend and he was doing Crosbie a favor. Little did he know…
Obviously, Te Rau is incredibly ashamed of his loose lips (and the fact that he cashed in on them) when Crosbie turns up dead. However, he gets to avenge his friend when Carver is arrested and transported to Seaview. While the carriage is en route, someone breaks in and bashes Carver's head in. The narrative never outright tells us it's Te Rau, but we get some pretty strong clues (like his long, hard stare at the lock on the door to the carriage before it departs) that he's the guy.