^^^ Much to his disappointment, he didn't become the leader and Tim came back to lead them as Red Robin before the series was cancelled within a few months, I think by issue #100 or so right around the time of the New52 reboot. The only Titan who didn't completely write him off was Ravager and even still she didn't see him as being a leader. The banter between Bat-Grayson and Damian was the only reason I ever bothered with a comic he was in, and the two together were an enjoyable read. Beyond that, I just don't care for him. I don't think Damian has the presence to ever be his own character, he'll only ever be the Son of Batman. I was happy for his fans when he finally got his own solo series, and I liked the idea of bringing Nobody back into it... but then they gave Nobody a daughter who's still hanging out with Damian and it just felt too forced. We JUST found out Ducard had this son... Nobody... now we find out this guy ALSO has a daughter who's been trained at birth to be a more brutal vigilante. 

You're forgetting Grayson was also the original hothead Robin and the only one to actually storm out of the Bat-Cave when Bruce refused to see him as an equal and not a sidekick. As Robin he was also responsible for a lot of early teen hero deaths and collateral damage earlier in the team's history and it weighed on him for awhile before he and Wally West both quit the team. He was still in Batman's shadow, but as Robin he couldn't be his own man. Hence becoming Nightwing shortly after. 

~KL~