Answers 1Add Yours
Gonzalo is an optimist; he's a great guy and considered "an honest old counsellor of Naples." I'm not sure what you mean about his role in the plot agaianst Prospero, as Gonzalo is the person who made sure Prospero had the things he needed to survive (food and water). In fact, Gonzalo didn't just supply Propsero with necessities, he supplied him with fancy linens and books, as well.
As for the secind part of your question, Gonzalo seems to me to be consistent throughout. He continues to be loyal to Prospero ands care for him. In fact, Prospero goes so far as to attribute Gonzalo with being a part of his providence or fate.