Originally Posted by
HsssH
He doesn't have to be a show-stealer to overshadow other characters. Its kinds why Moore killed Holms and Dracula in his LXG before the start of the series. Regardless of how badly written or irrelevant "popular" characters are to the main plot, people tend to pay more attention to them simply due to familiarity. Thats why almost every vampire movie has Dracula or some reference to him, because most of the viewers watching vampire movies, at some point, think "how Dracula works in this setting?".
With Damian, its likely that couple of irrelevant panels with him would attract more attention than 5 pages of Duke doing something important. Its really same argument that people make about Batman guess staring in other books - he is going to take control of the story because people care more about him than some random D-list hero.