So let's say that in a future Heridon Copper story, he learns that he's actually an Englishman that was raised by an American couple after his parents died under mysterious circumstances? Let's assume he was a newborn when all this happened and he only finds out 28 years later. His adoptive parents never bothered to tell him his true heritage for reasons I haven't decided yet. How would he feel? I get that he'd be pissed, but how would I properly express his emotions? Would he feel betrayed? Lose complete trust in his family? Also, how would I drop hints of this relevation through the series? I don't want to surprise readers by saying: "Oh, wait! Heridon's English and I never bothered to allude to this!" in the middle. Thoughts?
I'm only guessing how a person in this situation would react, but I think he might be in a state of shock to begin with. After the shock wears off, he might experience feelings of resentment, mistrust and loss of faith in the circumstances of his life. Maybe a crisis of self, as well.
Link, these are the questions you should form your own answers to, and make the answers the basis of your story. As for the latter two questions, you will only find those answers by writing your stories and fixing the problems when you encounter them. That is to say, experience is the best teacher. Now if you have written your story and cannot get something right, that is the time to ask specific questions. You won't find these answers in the planning stages unless you have already addressed them in other pieces you have developed to the limits of your current abilities.
I remember when my parents told me my father wasn't my biological father, but my adopted one. My real father had committed suicide before I was born and I never met him. When they told me, I was.... shocked, for one. Very shocked. I didn't want to believe it, either, so I felt a lot of denial. And I was really angry, and really hurt that my parents would keep that from me. I didn't lose complete trust in them, but I trusted them a hell of a lot less thereafter.