Who do the archangels report to?

They report to Creator directly and this is the most appropriate supervisory relationship. You personally see the value in being able to go to Creator to ask penetrating questions and gain insight and wisdom about things that puzzle you or challenge you in some way. This is still true for the angelics. They need guidance, and support, and healing at times as well. They can turn to their peers or to their leadership as well as to Creator directly, at their choice. The archangels can do the same. They can consult with one or many other angelics of all positions and they can go to Creator, as they have the most complex tasks at times, in coordinating very critical divine interventions. They almost always are in close consultation with Creator to have the full benefit of divine firepower, so to speak, brought to bear. It is simply the case that this is easy to do, so there is no advantage in taking things on unilaterally and putting others at somewhat greater risk by not having the full complement of divine wisdom on hand to refer to.