At the ripe age of 15 you created something no one else could, a supermolecule that enters the body and literally mends the body's wounds until there's not so much as a scar, but you had yet to patent it, so you kept it hidden.
One day word of your invention got out to the wrong type of people, and it and you became a highly desired object. After all, it's essentially immortality, and it works quick enough to be called indestructibility too.
When you created said invention, you were an orphan, developing a bond with all the kids of the orphanage, and taking care of them like your siblings.
That is why, when you found out you were desired, you disappeared in hopes the orphanage won't be used against you, no such luck.
One day, a rag is pressed to your mouth and nose, and you pass out, waking up in a dark room, chained down.
After months of torture, you hadn't given up the molecule, so they chose to go a different route...
The next morning every single kid from the orphanage you lived in are brought to your cell. "Don't you touch them!"
You watch in pain as the first gunshot goes off, struggling futilely against your bindings.
"I'll kill you! Touch them I'll kill you!"
You stare down in numb pain at the bodies of all your loved ones. They never gave you a choice... they never gave you the option of saving them, it was all to break you...
They didn't realize that, rather than breaking you... all they did was make you all the more determined to make sure they drop dead.
Meanwhile, after the orphanage incident, the bodies of the dozens of children are found, and it becomes known that you are the only living resident left... 'you have something that some bad people want'... TF141 realizes...
They don't know what exactly you have, all they know is that, if Makarov is willing to create such a huge scene it's something they need to make sure he doesn't get.
After a few months of searching, they find where you're being held, and hatch their rescue ploy.