I tend to only look into Premade backstories if one of my original Sims marries one, but they are interesting to read.
The closest I ever played to a backstory was in an Appaloosa Plains save. During a legacy one the heirs( of like generation 3 or something like that) marries Calvin Riffin whose best known for the fact that he’s raising his younger siblings and is really good friends with the Miller family who kinda watch out for him and his siblings. I enjoyed having my sim help raise Cornell and Chantrelle( the siblings) and made sure they stayed friends with the Millers. It was a really fun save!