ORIGINAL DESIGN SPECIFICATIONS
The android that became Thunder cat originally was designed for offensive actions in hostile territory, and covert operations. Her overall frame design was based off the successful OZ-F-frame MK2 android, which Professor OZ had used successfully in the past with other androids. She was equipped with prototype thorium nuclear batteries giving her enormous amounts of available energy to power her main form of offense, the projection of large bolts of lighting. As she was designed for covert operations, and thus required the ability to blend in with normal humans, she was not equipped with large heavy armor plating as that is very difficult to hide. Instead she as given a nano-motile layer of synthetic skin that allows her to create many disguises on the fly, and an adaptive skeleton that allows her to increase her size to a limited degree. As this system allows for growth, it does not really allow for shrinkage, so her base form was made as small as possible. The fact that building a combat capable android in a very small package was also more technically challenging simply made Professor OZ consider it a interesting challenge. Taken in combination, all of these systems would crate a highly effective spy, assassin, and saboteur. Her original operation plans were to sneak into some highly secure installation and then very quickly destroy the target then leave, using her limited shape shifting powers to sneak out in the confusion, as she may be an android and more durable than a normal human, she was not built for prolonged front line combat. In any sort of large pitched battle she would function as highly mobile artillery. Her positronic neural network was only designed for limited sentience, as giving full sapience to a android likely to be routinely destroyed and restored from backup seemed amoral and not necessary for the completion of its mission, as it could fake having a real personality long enough to infiltrate and cause the maximum amount of destruction in the shortest period of time. The need to be able to perform infiltration also required her to be able to eat food convincingly, this was achieved by a techno-organic artificial digestive system, this also allowed her to gain energy from any food that she would consume. It was not discovered until later that the engineers did too good of a job at mimicking nature, and that the system actually was effected by alcohol and other similar substances.
Originally a stray cat, she had been effectively adopted by the lab as a whole, and named 'Fluffy' by the expedient of picking a name out of a hat. She spent most of the time finding a warm spot to curl up and take a nap, or looking for interesting things to eat. This of course caused some consternation to the lab technicians who were running experiments on mice. It was this habit that also led to her effective addiction to catnip, as quite a few of the interns at the lab enjoyed watching the resulting antics. As there were many different experiments going on in the lab and in the complex as a whole, she got exposed to many different forms of radiation, mystic and eldritch emanations, mutagenic chemicals, super soldier serums, and who knows what else. The end result of all of this is that she was a rather accident prone cat and was likely well on the way to becoming something more regardless of what happened next.
The batteries of the android required a huge investiture of initial power to properly condition them for the loads that they would be sustaining. This process required the entire output of the generators at the laboratory, and as a result, there were power cables laying all over the place to try and get the required power together. This all came to a head when during the effort to get the combat android up and running for the first time, fluffy was absently chewing on a power cable behind a piece of equipment where no one was watching. When the switch was flipped, fluffy had managed to chew through the insulation and was working on the copper beneath. The resulting short burnt her to a crisp and instantly ended her feline life. However, her soul followed the trail of electricity and ended up inside the now active android. At first she had no idea what was going on, and neither did the professor, who was quickly looking at the AI code to try and figure out why the android was mewing. At least until the smell of burnt cat spread through out the room. The first words that Thunder Cat heard and could understand were the professor going 'huh that is funny, it is acting weird'. It took Thunder Cat several minutes before her soul finally settled in well enough into her new body that she could access the full capabilities of her new cybernetic brain and gained the ability of speech for the first time. It was only because her new brain already had tons of information on human interaction and conversation already pre-loaded into its data banks that allowed Thunder Cat to be able to communicate effectively what had happened. Once the shock wore off, the professor immediately had a fit of maniacal laughter and shouts of 'its alive' before one of the interns handed him his bottle of medication that kept his science related mimetic disorder in check.
Thunder Cat spent the next few months inside the lab getting used to her new body as they slowly dropped the limiters on her powers as she got used to them. It was also at this time that a mystic from the university was brought in to try and analyze her. The mystic confirmed that he could sense a real soul inside the robotic shell, and that it seemed to be in tune with its new body as if it had been born there. Which settled the betting pool that had been going around the lab, which had been doubtful about the soul business, or thinking that the soul would not have enough of a connection to the artificial body to remain there indefinitely, as it could be said that she was a spirit haunting the android. As an experiment the mystic began teaching Thunder Cat some of what he knew, and she proved to be an able learner and was able to learn a few simple incantations, proving the mystics thesis that all that was needed to perform magic was a soul. These exercises had another side benefit, she discovered that she could use her soul to dump raw mana into her body to cause it to repair itself. It was determined that while she was able to access the knowledge uploaded into her data banks, and could process information very quickly, thus making her highly knowledgeable and intelligent, she was still sorely lacking in wisdom, which can really only be obtained via experience.
Once it was determined that she was not a danger to herself or others and that she could function in normal society, the professor took her and several of his other androids on a tour of all of the major universities and laboratories. One goal was to show off the results of his work, as well as to drum up more research grants. It was during the trip to Japan that she really became a media sensation, as the Japanese love cute things, robots, and cat girls. It was because of this triple threat that she almost immediately developed an otaku fan club. Do to her status as a minor celebrity she appeared in several day time TV variety shows. It was this that caused her to meet what was to become her nemesis, a girl by the name of Red Tiger. Red Tiger was the leader of a ninja clan, however she was using her own cat girl status to be a minor celebrity herself. It has been speculated that the main reason that Red Tiger was even in the entertainment business at all was due to her extreme vanity. It was this vanity that led to her becoming jealous of this newcomer who was stealing attention away from her. Things came to a head when they both entered the same bikini contest. Thunder Cat's win sent Red Tiger over the edge. Later that night some ninja assassins came to her room with the intent of assassinating what they thought was nothing more than a domestic android unequipped for any form of combat. 50,000 volts later the ninjas were lumps of quivering jelly on the ground. Thunder Cat's unwillingness to die like a good rival infuriated Red Tiger who responded by sending ever escalating ninja kill teams after her. However, Thunder Cat managed to defeat every team that was sent, oftentimes simply by being in the same room as one of the other combat androids of the professor's. After not too long the professor got fed up with cleaning ninja bits out of his luggage and took everyone back home. Once back home Thunder Cat was allowed to wander around millennium city unsupervised to let her get better at dealing with normal people and to have her learn some much needed wisdom. The only real problem with this is that while her body may appear to be that of a young girl, it was still inhabited by the soul of an adult cat. A naive, momentary, impulsive, and air headed cat, but an adult cat nonetheless. Fortunately her abilities as a combat android got her out of just about any trouble she could get herself into, including cases of being tricked into windowless vans by offers of candy. It was after the professor got tired of picking her drunk ass up from yet another frat party that he started seriously looking into finding her a school that would be better suited for her. This was all put on hold when the Quilarr decided to invade Millennium City. Thunder Cat managed to aid in the defense of the city, and immediately got hooked on being a 'hero' mostly because it allowed her to fully use her powers with out getting yelled at.
Given that she is an android and has few functionally organic parts, she is oddly enough still affected by catnip. Not only is she affected by it, but she has also retained her effective addiction to catnip from her days as a regular cat. Some metaphysical experts at the university maintain several theories on this. First that all of it is just a psychosomatic reaction left over from her house cat days. Second is that there is enough organic bits for those to be affected and sense the whole android is effectively haunted by a cat ghost it responds appropriately. Third is that it operates similar to the drugs many tribal shamans use to go on spirit journeys, and thus helps her robotic form keep in touch with her soul. There are also several experts that believe that it is all three. Regardless, she shows withdrawal symptoms if denied catnip for too long, also psychics that have witnessed her in this state have reported that her soul seems more distant. Additionally, it has also been observed that she will "pull a Christine" when given some catnip, completely recovering from damage that should have been rendered her completely inoperable. This is believed to be possible for the exact same reasons as the aforementioned car in the novel by Steven King, the haunting spirit simply reforms the physical body.
There is currently a debate going on if it would be better to have her kick her catnip addiction or if to do would be more detrimental to her health. This is also given that the observed effects of catnip thus far have been; impaired speech, likened to that of cats seen on the internet, lowered dexterity, impaired judgement, increase in appetite, sleepiness, and an increased desire for physical contact.