Relevance is key. It has to be related to the main story in some way. Also, it should be interesting on its own. For example, if the main story is a love story, a back up story about the characters' families and how they influenced their views on love would be relevant.
One important element is that it must be well - paced. It can't be too long and drawn - out if it's a back up to a main story. It should also have a purpose. If it's in a news article, the back up story might be used to provide different perspectives. It should be concise enough to not overshadow the main story but detailed enough to enhance it. For example, in a report on a natural disaster, the back up story could be about the efforts of local volunteers, which gives a more human - centered view while still being in the context of the main disaster story.
One key element is the unexpected opportunity. The backup goalie gets a chance to play when no one really expected it. Another is their performance. They have to perform at a very high level to turn the situation around. Also, the team's reaction to them is important. If the team doesn't support the backup goalie, it's hard for the cinderella story to unfold.
A good back story should also have a sense of causality. Events in the back story should lead logically to the character's current situation. For example, if a character is a successful entrepreneur, her back story might include early business failures that taught her valuable lessons and ultimately led to her current success.
One key element is the wealthy setting. The 90210 zip code represents luxury. Another is the high - school aspect. The characters' experiences in school, like cliques and popularity contests. Also, relationships play a big part. There were romances and break - ups among the characters.
One key element is the nuclear apocalypse that destroyed Earth. Another is the Ark, the space station where the survivors were living. And of course, the 100 delinquents being sent to Earth.
Another element is the determination of the women. They didn't accept the status quo and decided to fight. For example, they started to demand equal work opportunities.
One key element is a purpose. For example, a business aiming to solve a particular problem in society, like reducing plastic waste. Another element is authenticity. The story has to be real and not just made up for marketing. For instance, if a coffee company says it sources beans directly from farmers and actually does it, that's authenticity.
One key element is its evolution from Gastly and Haunter. Another is its connection to shadows and darkness. Also, its mischievous nature is important.
The key elements are the Smurfs themselves, their forest village, and Gargamel. The Smurfs' unique characteristics and their village setting are important parts of the back story, and Gargamel as the main villain.
If it's Guts from 'Berserk', one key element is his origin from a hanged corpse, which sets him apart and makes his existence somewhat of an outcast from the start. Another is his time as a mercenary, where he learned combat skills and survival tactics in a harsh world.
One key element is his desire for power. Bowser wants to rule the Mushroom Kingdom. Another is his rivalry with Mario. Their battles are a big part of his story. Also, his relationship with Princess Peach, as he constantly tries to kidnap her. His army of minions is also an important part of his back story as they help him in his evil plans.