Most people associate them with positive and negative emotions, which is somewhat correct but not 100% or explain the naming conventions.
Both trust and fear are psychological factors that can make somebody susceptible to being control or manipulated. Most times you will listen to a parent or older/authoritative figure because you trust them. If you being held at gunpoint you will listen to that person, fearful of what they going to do if you don't.
It fits with what we seen of the show, the more trust or fear you have, the less control you will have over your self. Also, the way trust and fear works is similar to a psychological idea/concept of "locus of control":
- The trust system have a more external locus of control as it is heavily reliant on your environment (people's perception and willingness to give you trust)
- The fear system have a more internal locus of control as you have more control over creating your own fear particles through your own negative emotions. Also, I believe in the show, somebody mentions how fear is easier to manage, use, or control than trust.
The trust system in TBHX is closer to celebrity or idol culture, which I think most of us know by now. Once you create a image or a reputation on something, your fans will mainly know or want you to keep doing that. If you stray away from this image they have of you, they could be displeased and no longer be a fan.
The fear system is hard to gauge on what aspect they take it from as there are multiple mental illness involving fear. However, if I have to say, it is mainly based on the fight or flight response factor, more particularly the fight aspect. Most to all of the times, when people are affected by fear they will almost immediately go on a rampage or try to attack something. But, realistically almost any aspect or concept of fear would make sense in relations to the Fear system, whether it is PTSD, insecurity, paranoia, and etc.