Maurice is your stereotypical annoying older brother. One of the first things he does is poke baby Ursula in the face, and later we see him smash birds' eggs, shoot a fox, and step on a kitten, although he swears that last one is an accident.
His bratty nature becomes more and more despicable as he gets older. His friends from school aren't the nicest boys (which is the absolute least we can say, seeing how Howie rapes Ursula), and he becomes a scab during a labor strike. After school, he gets married, works for Home Office, but is always finding a way to look out for himself (like using his government position to get himself a pretty female driver in a time of petrol shortage). When Sylvie commits suicide, the first thing Maurice does is loot Fox Corner and sell all the furniture for money. Classy.
No matter what happens in Ursula's many lives, Maurice always acts like this, and Ursula never tries to change his nature. Maurice is a jerk, but at least he remains constant.