In a magical world there is a tribe of people divided into termite-like castes. They live in the wilderness, far from most regular humans. They are effectively human; fully conscious and conscientious individuals who are exceptionally loyal to their own kind, not simply because of their isolation from others, nor because of the risk of attack by humans. Their society is split into three castes with specific roles: Queens, Drones, Guards.
Queens are rare, large (2.4m tall), live for centuries, and are almost constantly pregnant, giving birth to all three castes. Drones are common, small (1.2m tall) infertile females. Guards are uncommon, very large (3.6m tall) and strong males.
Let's hand-wave the issue of how Queens are pregnant so often and effortlessly, that's not the issue here. They are pregnant often, with multiple births, and this and labour isn't much of a big deal, allowing them enough energy (just about) to be in a position of leadership. I am interested primarily in the psychology and physiology of the castes, in so far as how it can help explain norms of thinking and behaviour.
Drones and Guards are almost absolutely obedient to the Queens. This is a psychological predisposition which makes their behaviours likely, and is not a physical limit to their ability to harm or rebel from the Queens, which are not by any means capable of fighting. Guards do not abuse their strength to bully the others. Given this context, what psychological characteristics are required for Drones and Guards to be loyal to the Queens, and for the Guards to lack aggression towards Queens and Drones?
I would like answers to discuss psychological functions/dysfunctions in humans in order to understand how these castes would think differently in order to maintain harmony. Physiology is obviously part of this, but I would not like it to be the primary issue outside of how it influences the brain/mind.