Creating a fictional character is a great deal of work...and fun. The characters can be crafted out of the barest whiff of truth or can be grounded in a composite of the best attributes imaginable.
A character should be treated with the same care as the story itself. I've written before that finely crafted thriller hangs its plot lines on real events and real places, giving the reader more to grip onto. This makes the reading experience more engaging. If a story contains a larger-than-life protagonist, then the backstory, no matter how faintly alluded to, should answer why or how that character came to be. The backstory should always support the created character and not run in conflict with it.
Even a seemingly small detail like where that character may have gone to college is an important part of their persona. Feel the difference when a character "shopped at only the finest boutiques" and "prowled the clearance racks at the local thrift store." Where he or she shopped could be the most inconsequential aspect of the story, but that one detail shapes the reader experience of the character and thereby shapes their experience of the story.
Choosing my character's alma mater was an easy choice. Intelligent, robust and hailing from New England, Bowdoin College was a natural fit for Jessica Wyeth. By connecting a fictional character to a real college, the character becomes imbued with the perceptions the reader holds for that institution and becomes someone the reader can relate to or identify with. Conjuring that image can take pages or it can take the faintest of brush stokes, but it also has to mean something.
A good thriller doesn't clutter itself with irrelevant facts, but it does have to contain enough detail to help build the tension. Supporting the character's traits with real life details fleshes out the character and makes a fictional story more real.
This to the Bowdoin Daily Sun tells why I chose it for my character's backstory.