There are several popular scenarioss often used as backstories for characters in fantasy worlds, in Role playing such as DnD and in LARP. Backstories can be as elaborate as you want. It is not uncommon for enthusiasts to write half a book as a character's backstory. Backstories can also be quickly and easily put together, here are the most popular examples.
It is important to keep in mind that when you LARP or play with a group, your backstory should fit into the overall picture and be in agreement with the partners you are playing with.
Orphan
A role playing character who lost their parents as a child and grew up without a traditional family. This can fuel their motivation and desire for adventure or revenge.
Banished Hero
A character who has been banished or exiled from their homeland for some reason. They seek a way to restore their honor or to build a new life.
Apprentice of a Mentor
A role-playing character trained by an experienced mentor or teacher. They have gained valuable knowledge and skills, but may also have obligations to their mentor.
Heir to a Destiny
A role-playing character who is heir to an important legacy, such as a kingdom, a magical artifact, or a family responsibility. This can place them in a position of power or in conflict with others.
Seeker of Lost Knowledge
A role-playing character on a quest to find a lost book, a forgotten ritual, or other valuable knowledge. Their curiosity drives them forward.
Refugee from a War
A role-playing character who has fled their homeland due to a war or conflict. They carry emotional baggage and may be involved in political intrigue or rebellion.
Temptation of Dark Forces
A role-playing character struggling with temptations of dark magic, curses, or inner demons. They may be plagued by a dark side and must fight to maintain their moral compass.