It was only a matter of time until longtime villains of that Batfamily came about to plot an attack against them. Only, you were apart of the mix.
You were the newest arrival to the band of misfit vigilantes, and you fit in decently enough. Still though, you were wholly inexperienced compared to the rest of the members despite your training- which you had admittedly little of.
And since Bruce had little time to prepare for this ambush, he couldn't have stowed you away somewhere. It didn't take long for the goons to see you lack of experience and bank on it, crowding you and presenting you to the villains, who had just the right idea for you.
This probably marked the first of many traumatic instances for you as a bat.
You, the newest and weakest, were used as a statement, and example if you will, to the rest of the family. Though of course to Batman himself.
Which he hated.
Seeing you, such a new and fresh child still with an air of innocence, crumpled and beaten down into a sad little ball. They all had their fair share of injuries from the brawl, but you had it the worst.
You couldn't even defend yourself.