Ann Maria Castro was only sixteen when she fell pregnant to her then boyfriend. The young man, Miguel Donahue, stayed only long enough to see Catalina born before leaving with no word. Ann Maria did her best to raise the rambunctious girl, but her own parents were not wealthy and she was forced to scrap by on what little income she could find. As a child there was little that Catalina didn't get in trouble for. She had a brilliant mind, but lacked the focus and dedication that would see her truly excel. Her teachers often exclaimed that she could do great things if only distraction wasn't so easy to find. Though, in later years Cat often wonders if it was simply because they weren't teaching the right things. It was only when she chanced upon a television screening of a spaceship launch that Cat was able to focus her talents on something that earned her interest. She discovered computers, mechanics, programming, and the many things one could do in today's world with a good head for technology.

Cat learned quickly, and before she knew it her considerable talent with computers was being put to the wrong uses, namely hacking into whatever database she thought would prove most entertaining. It was this little hobby that first put her on San Foret's radar, after her successful foray into a high security database raised red flags at the spy school. When a team was sent to silently investigate, they found a young girl on a computer system that she had put together herself from second-hand scraps and pieces acquired for her by a distant cousin. Naturally, an invitation to attend Academia di San Forêt was sent, and Cat would have been stupid not to accept, for such opportunities did not often come to those in the poorer suburbs of Mexico City. Her mother, under the assumption that San Forêt was a prestigious institute of technology, would not hear of her daughter denying herself such a chance in life, and in little to no time Cat found herself leaving family and friends behind.

The Academy proved a new challenge, one that Cat found she had been waiting for. No more did she have to use ancient technology or horde her allowance to buy crappy pieces of hardware. Here she was presented with the best money could buy and offered every opportunity in the world to expand her knowledge. Her English, already semi-fluent when in Mexico, was strengthened and she was able to add sprinklings of other languages to her repertoire, picking up most relatively easily. If anyone was concerned that her heart defect might impact her work or put her or her peers at risk, they were soon silenced by proof to the contrary from the young girl. Diagnosed as a child, there was little her struggling mother could do other than heed the doctor's advice. Cat was lucky though, for her condition was not so severe as to completely limit her. She might not ever run a marathon, but she'd rather be tinkering with a car engine or programming a computer instead anyway. While she is not ashamed of her condition, she refuses to be treated differently because of it and is therefore unlikely to tell any other than those who must know and her closest confidants.