(Based on an old favorite theory of mine that Han and Boba were Odd Couple-esque roomies at the Imperial Academy. Obviously Episode II had other ideas...)
 

     Here's the unauthorized, but true, story:

     He was actually Han's old roommate back in the Academy days. Back then Han was always getting the chicks, and Boba (Francis, as he was known back then) wasn't exactly a ladies man. While he might've had his studies to attend to, and had dreams of becoming a war hero, deep down he always wanted to be just like Han. Eventually both got kicked out of the Academy (Han for rescuing a Wookiee from slavery, Francis because of too many demerits for not keeping his part of the room clean).
     Han went on to become the reliable, sought-after smuggler we've all come to know and love. Francis found odd-jobs here and there, ranging from working on the production line of a blue milk cannery, to clerking at a Mandalorian surplus shop.
     It was there that he discovered the now infamous Mandalorian uniform. It may have made him a one-man army, but that's not what was on his mind. No, thought Francis, this suit would make him an intergalactic chick magnet.
     After quitting his surplus shop job, he eventually got to support himself by being a small-time "bounty hunter." Sure, that's what he put on his tax forms, but in reality he did nothing more than take up minor jobs like finding lost pets.
     Months went by and through some wacky mix-up, ol' Francis was mistaken for some big-time bounty hunter (who had actually died years earlier in a blaze of glory, unlike the man who would go on to assume his identity). And thus, "Boba Fett" as we know him was born.
     It was only through good PR on his part and an exaggerated resumé that he was able to land his first job with Darth Vader. That job had him hunting down an admiral who had betrayed the Empire. But Francis -- with his in-helmet corrective lenses having been jarred loose -- accidentally killed Vader's publicity agent instead, via disintegration (hence Vader's firm warning to Fett about disintegrations in The Empire Strikes Back).
     Alas, Francis never was able to hold on to a steady romantic relationship, as true love relies on much more than mere costumes, weapons, and gadgetry. In the end, Francis met his demise in a fashion that only he could, and is no doubt still being digested even as of this writing, all the while learning the true meaning of pain and suffering. That's what you get when you pretend to be someone you're not.
     Thanks for the lessons you've taught us, Francis; we owe you one. You'll be missed, you poor unlucky bastard...
     And that's... the rest of the story. Good day.