User blog comment:Thailog/Ep. 207 "Depths" discussion/@comment-432124-20120609222118/@comment-432124-20120614072904

Well, Regulus, those time-travelers wouldn't have to spend too much time on the show. They could just be recurring characters that escort Bart and some other Team members to where or when they need to go and then just show up every once in a while to give information or team up with them in order to take a step in changing the future.

Besides, I think that it's necessary because otherwise, as the end of "Bloodlines" indicated, Bart isn't gonna completely fulfill his objectives with his current methods. The changes to the future aren't gonna come slowly as the story in the present progresses. As Peter David quotes, "The way we’re playing it is that there’s one timeline and only one, and if you change it at some point, the ripple effect causes everything from that point on to change in order to accommodate the revision." Source: http://www.peterdavid.net/2012/06/02/spoiler-thread-young-justice-bloodlines/comment-page-1/#comment-721927 This means that from the moment that Bart showed up in 2016, everything should have changed to accomodate the revisions that he made and was going to make. Otherwise, I'm pretty sure that Neutron would have had to wait at least a few hours for the changes that did come, but instead it was shown that they came as soon as Bart disappeared. In other words, unless another time traveler shows up, Bart's interference isn't gonna make much of a difference to his future.