The Children's League is an organization created after kids were sent to rehabilitation camps. They are set out to breaking kids out of camp and taking down President Gray. They broke Ruby Daly out of the camp Thurmond and largely planned to use her as a weapon. The of the Children's League seems well. However, we see in Never Fade that the leader of the league, John Alban, has the only objective to kill President Gray.
When Ruby joins the Children's League, she finds out that certain agents have been killing psi kids, especially the younger ones, and has to save Jude, knowing that they will kill him too. In In The Afterlight, Ruby sends away agents that plan to sell kids out to PSFs, and the League becomes a better place, and more focused on breaking kids out of camps. In the book, Ruby frees the kids from Thurmond, due to the help from greens in the league.