What is the contradiction between brother and sister in The Lego Movie 2: The Second Part: Part II?

In The Lego Movie 2: The Second Part: Part II, the contradiction between brother and sister is because the brother can't accept the violent participation of his sister, which leads to the estrangement between them. In order to save it, my sister wants her queen to marry the leader of another Lego world, so that she can reach a settlement through marriage. Finally, brother and sister shook hands and got back together, and they also grew up and became better themselves in the process of eliminating barriers.