Awhile back I tried to write a series of short stories based on a old man telling a child about all of his victories in life. After writing it for awhile, I encountered this dilemma: how do I develop/make a character good, if all he does is win? After a couple weeks of writers block, I came to a conclusion that I thought might be worth sharing He/She Wins| But At What Cost? Just like it sounds. At what cost. So your character never loses a battle. Technically. Here is a good example: You have a soldier, who has a goal to take down a terrorist organization. Sure, he succeeds in taking the group down, but his family is killed in the process. A much less extreme example would be if a a hopeless romantic gets the girl he has been dreaming of- but loses his best friend while doing so. See where I am going with this? If your character never loses the battle, you need to make him lose in other ways. If You want, this can also open your character up to questioning his achievements in the first place? Was getting the girl worth losing his friend to him? Do the benefits outweigh the cost? In the end, you are asking yourself the same question as you thought you wouldn't: what does he lose? because indeed, that is what this is all about.
True, alot of times stories with invincible characters get boring after the same thing over and over. #the hero saves the day again Superman, dragon ball z, naruto, bleach. All shows, comics with overpowered hero's that always come out on top, through the same methods, getting the same results. Scooby doo is a flawless example It makes sense that a writer would want to throw some sort of twist in the river to keep the read/watcher of the story from see the same ending for the entire 300 episode series. Even still, alot of times that's exactly what happens
A common example of victory-with-price I enjoy is that the hero is on borrowed time, before a major catastrophe occurs. Off the top of my head I can think of Puella Magi Madoka Magica, where girls get magical powers to fight off horrible monsters called "witches" before finding out that they themselves eventually turn into witches from using their powers too much. Although that example is a bit esoteric, I think more commonly people just use some kind of medical dilemma, like cancer or some other disease. Also, your example of "an old man telling stories" reminds me of Big Fish. Maybe your story isn't the same, but it's about an old man who tells his son wild tales of victory and adventure. His son never believes his stories until he finds out, while they weren't true, they were all based off real, most more lackluster events. In this case, he never paid a price for his victories, but rather his victories just weren't that impressive to begin with.
It's funny you should mention this, because I recently plotted this into a superhero story I'm writing. The MC who only recently discovered her powers, initially became a hero because she wanted to be popular and make money through things like product endorsements. Very self-centered goals. During a fight with a super villain that is tearing up a city block, a man asks the hero to help him save his daughter who's trapped under some rubble. The hero blows him off to finish fighting the villain and wins the battle. Afterward when she's basking in the applause of the crowd, she hears someone crying and notices the trapped girl. Her father managed to free her, but ended up being killed by more falling debris in the process. This one event has multiple ramifications because the hero realizes the girl's father is dead because she couldn't be bothered to help him. The MC isn't so much 'evil' as just narrow sighted and naive, not thinking about the consequences of her actions. This makes her re-evaluate why she wears her costume, and is part of what makes her start to grow up. The second ramification is that the girl blames the hero for her father's death. Because of this she's slowly consumed by anger and a desire for revenge, and will eventually show up a few stories later as a psychotic, cybernetically enhanced villain, intent on killing the hero. She also becomes her worst enemy nearly succeeding more than once, all because the hero inadvertently let one man die to win a hero/villain fight.
That's not really the point of Big Fish, and I'm not sure that system would work in a short story setting
