Think for a moment - what does it take to build good, average trust, enough trust to believe what a man says on face value? Heck, it might take half a lifetime of honest dealings to build such a foundation of trust. Between neighbors, I'd say a handful of years of familiar association to build that kind of trust.
Why do I bring this up? I read a book - A boy, early teens, was living and working with his teacher for an indeterminate number of years. The boy being young did his chores and he did his lessons. but he was also off doing his own thing, which the teacher of course didn't approve of much. Sounds pretty normal, doesn't it. So as the story progresses, the teacher has to blast off on some errand, and it's apparently time to send the boy to another teacher for further training - off they go.
This boy, being raised in a tiny, back-water community, is the epitome of naive, so it's not too surprising that the first person he runs into on his journey tries to rip him off. His sole source of currency is a pearl, and the innkeeper is willing to trade that for one night's stay and a meal. Thank goodness he's rescued by a traveling trader, who will pay him a life's wages for the pearl if he will just come with them to their home on the coast.
Trust - go? don't go? Who do you trust?
To sweeten the deal, the trader will pay his way and feed him as long as he travels with them to that end. Yeah, I think I'd take that deal too, but trust is still an issue. Just how much can you trust this merchant or his beautiful daughter, who is of course batting her eyes, haha.
So trust figured in quite strongly throughout this story, and most of the time it was handled well enough, but when you never question strangers, trust is being taken advantage of.
Because of an altercation a couple days later, the traders went through the boy's belongings and read a letter of introduction written from his old teacher to his new teacher. It had been sealed and the boy of course trusted his teacher and had never read it. The letter ended up being a death sentence to be carried out by the new teacher. Suddenly the boy was out for revenge. He would go to this teacher, but instead of going there to learn, he'd go there to be the one to kill first. There was absolutely no question that this letter might have been forged and the agenda sculpted to fit an agenda of his companions of whom he knew very little really. That was not the case, but still there was no question.
Okay so this is a YA book and such complications might be a little too much for young readers, but I think even young readers could have grasped this doubt. Who do you trust here? The teacher you'd known for some years, or traveling companions you've known for only about three days?
Later, much farther along the trail, there is a much more blatant mishandling of trust. They meet a man, another boy of like age, on the trail who then leads them to their destination. Upon a very first meeting, the new teacher, who thanks to a forged letter of introduction that said something quite different, wanted our trusting hero to kill the boy who'd led him here. There was no explanation of why he wanted this done, so maybe once again it was a means of establishing a form of trust. Our hero immediately goes to this boy and, after asking him if he trusted him (again why should he), he tells him what his teacher of however long wanted him to do. Of course he immediately believed him and they were allies in seeing to the demise of this teacher.
Trust - how do you manage it in your manuscript? Treat it as if it was a fine sample of blown glass, because it is. It is really quite fragile.