Before you plunge into your fantasy epic, there are a few checkpoints you need pass in order to continue. This relates to your main character, who will make or break the story. First off, is your main character extremely nice to others, to the point of annoyance to the audience? Do these characters never stop being nice even when insulted or seeing one of their friends going through a rough patch? Also, is your character potentially the weakest party member in your story's group of explorers, both psychically and character- wise? Finally, does this character have the cliché blond hair and blue eyes, which are usual signs of an unrealistically nice character? If you answered yes to at least two of these questions, then congratulations, you have created a one note goody two-shoes character that nobody is going to relate to in any way. Your potential fantasy epic is now dead!
When it comes to these types of characters, nine times out of ten, they end up being the death of an otherwise solid storyline. This type of character is one of the most overused out there and almost always results in the character ending up being flat. By the character always being positive in any given situation, relatable aspects of the story are lost. If your main character is always trying to save the bad guy even if their actions are completely unforgivable or try to be the peacekeeper in a situation that could easily be fixed on its own with time, the audience gets frustrated from the slew of predictability in the storyline. It is like having an overbearing parent, only ten times worse. The worst part is in battle, where they usually end up being the weakest when it comes to any type of combat. They become damsels in distress and almost always find themselves saved by another team member again and again. Characters like these lack any dynamics or unpredictability, making them a snore for audiences to try tolerating.
The reason these types of characters exist also can be connected to another cliché that should be avoided like the plague; the creator's pet. These characters usually are based on the authors themselves, thus receiving special treatment in the plot. It would not be much of a stretch to see in this situation that other characters in the plot do suffer both psychical and mental pain from the ailments given from the overall adventure. Heck, these other characters could end up being completely written out of the story as well from their untimely death. However, because they are the author's favorite, the sickly sweet character stays around for the entire plot line with no explanation at all as to how they made it through while much stronger characters perished. With these two clichés combined, unnaturally nice characters are the cold sore to fictional writing.
If you still love your nice character despite hearing all of this negativity connected to them, there is a simple solution to the problem. The solution is simple; make the character have realistic flaws and be just as prone as the other characters to being trapped in a long slew of nasty dog days. In fact, making the nicest character more prone to breaking despite their seemingly perfect exterior makes for quite a complex, realistic persona. Seeing that this kind of character can be equal to their comrades in the emotional spectrum helps to build up the kind of person they truly are in the story. The best example I can find of this is towards perhaps the most selfless character from the anime Puella Magi Madoka Magica, Sayaka. Just wanting to heal the love of her life so he would be able to play the violin once more, Sayaka made a contract to become a magical girl. At first, the new job looks like a great fit to her until she realizes the whole process of transforming into a magical girl basically turned her into a zombie, as her soul was extracted from her body and placed into an item known as a soul gem. The dark truth slowly pushes Sayaka into despair, making her reject the idea of being in a relationship with the boy she helped because of what she became. Worse, her fighting skills are comparatively weaker to other magical girls, giving Sayaka the inability to fight former witch minions called familiars before they become witches themselves and harm unsuspecting humans. This causes her to go into a complete mental breakdown that makes Sayaka see herself as useless and a self-made plague on the world. These negative feelings seal Sayaka's fate as she is transformed into the evil witch Octavia to the horror of her friends. So she cannot harm anyone in this form, Sayaka later has to be killed by another magical girl, leaving her entire story a self-made tragedy and a lesson about the dangers of being too kind.
Sayaka is the example of a nice character done right through her many trials that lead to massive amounts of development, even if the final results were not desirable for her. With characters like Sayaka in existence, I do not know why more writers do not try to invert the trope by adding relatable situations that shows other shades of what would have been a bland character. Through these kinds of situations, audiences grow to love the character and the story they are being presented with. It is killing two birds with one stone metaphorically speaking. If you want a character with an extremely caring personality, be sure to show there are more than one shade to this particular person. Give them secret fears, flaws that could lead to either their advancement or complete downfall, or best of all some type of internal conflict. Do that and your character becomes potentially a complete highlight of the entire story.