Here's an idea pinched from the Baldur's Gate series: How about implementing a background button on each character's stat screen. When pressed, this button could activate a 'Background Event', much in the way 'Step Events' have their own events.

You can already do this for NPCs, using either the "talk" event (camp) or "examine" event (view screen), both of which may be renamed something like "Background". It's hard to see how you could have a background event for PCs unless the player defines them at the start. Hope this helps.

The NPC's could have pre-made background text added by the user in the editor. That's not too difficult. It would be a harder to let the player add background text for created characters while playing the game. I'd need to implement a text editor within the game for that.

Maybe it could be done as a separate text file. Character Bobo would then have Bobo.chr, Bobo_icon.pcx, and Bobo_bg.txt. If the text file is present the engine will enable the Background button and display it. Sound reasonable?