I will honestly say that this is an original idea. I would have never seen a GL and HP crossover as a viable option.
You have actually found a way to introduce that crossover.
I look forward to anything else that comes along in this fic and will be honest, hope to be surprised more and more.
One set of questions:
Is Voldemort a Black Ring Bearer?
Is Malfoy Sr. an Orange Ring Bearer?
(The one who came to mind for me when I realized the setup for this fic was Ron, but you've already shown him as a non-bearer. The only other good option for the Orange ring would be Bagman, but he is mostly a minor satellite in HP."
Author's response
Tommy's going to be a black ring bearer. I haven't thought about an 'Agent Orange' though. Other Lanterns and DC heroes are coming in this soon though.