This is basically my theory that came to mind of what Fidget was like back then before and after turning to Ratigan. One-shot!
It all started when Fidget, the bat was born from parents who loved him and he loved them back in return. They spent as much time with him as they could, notably since he was homeschooled by them. That's not to say that Fidget didn't have any friends. He had neighbors who had kids that were homeschooled, as well; so, he wasn't alone. Before they educated Fidget, they bathed him, although he splashed every once in a while, and thrown stuff; despite this, the three bats chuckled because it was amusing. After all, he was just a newborn and hadn't known any better. Then, they fed him and made him laugh by making funny faces and played peek-a-boo because bats like peek-a-boo. Right away, the wee small infant bat really enjoyed the game, peek-a-boo. Curious, Fidget decided to try it, too and giggled. Seeing how happy the baby bat pup was, they laughed with him, carried him, gave him a hug, and patted his back.
At bedtime, when the boy bat has grown up to be a toddler, he said, as he hopped into bed, "I want bed bed!"
The next night, Fidget said, "I want beddy bye!" Every once in a great while, he hung upside down just as his parents do.
As the bat grew older, his father bestowed his son a black cap as a gift.
Years passed, he became more energetic and rambunctious. Of course, that's where he got his name "fidget". That was when his parents trained him how to fly.
In the future, Fidget chased after his runaway ball to the lake, where the leeches ate up his left leg. He waited less than an hour before doing so. In his pleading eyes, begging for help, he saw his parents momentarily arrive to his rescue and took him to the hospital, where he received a peg leg. It took some time for him to get used to walking with a peg leg.
Days passed as Fidget grew accustomed to his new leg. One day, when he was flying, he all of a sudden landed funny on his left wing. Again, his parents were immediately distraught and swiftly sent him back to the hospital so that his doctors could examine his dislocated wing. Fidget's doctors informed his parents that he wouldn't be able to fly for a while until it actually healed, then one of his doctors said, "And be careful with that wing, okay?"
Fidget nodded in recognition, although he didn't know better than to go in the water to get his toy back and break his wing days later. In his heart, he vowed to his doctors that he will be cautious.
Months later, when Fidget discovered that his old homeschool mates moved, his parents had him go out and make new friends. He met another creature that was different from his kind. It was a girl mouse. She looked much younger compared to him. Her name was Olivia Flaversham and he, too, introduced himself to her and they became best pals. After getting to know one another, they played outside all day long until it was time to go home to their folks. At the end of the day, the bat's kindred hadn't scorned him just because he was friends with a mouse and they had nothing against it, but they weren't the only ones, the mouse's father also liked the idea of bats and mice being friends.
In this day and age, Fidget had grown up into a young man, despite the circumstances of his peg leg and of course, his broken wing. He was about ready to spread his wings on an all new adventure.
Night had risen and it was when a rat with a black suit came with a cape and white opera gloves in the name of Ratigan approached and assassinated Fidget's parents. Fortunately for Fidget, he fled, although his parent's mournful words echoed in his mind: "Fidget, we can't make it. Run!" and "We love you, son!" Even so, he wished he could help, but they didn't want the rat to murder him, as well. "I love you, too!" Fidget replied.
Ratigan, a no-good sewer rat killed Fidget's parents in an instant that very evening, but their only son managed to escape and thanks to them. Considering that, the bat's parents insisted he ran from the callous rat. As the young adult bat took off running, Ratigan vowed to himself, "I'll pursue that little brat bat if I have to terrorize all of Mousedom!"
In that same night, Fidget came across a street that read 221 ½ Baker Street. Without a moment's hesitation, the bat knocked on the door and a housekeeper looked utterly confused. "What brings you here this evening?" she asked. Her name was Mrs. Judson.
"You see, my parents were killed by a rat tonight," said Fidget, his voice urgent.
Mrs. Judson was aghast. "Ooh, that's terrible!" she sympathized, as she escorted him inside, "Mr. Basil. This young man would like someone to look after this traumatized fellow."
In an instant, a young man mouse, who is a detective in the name of Basil of Baker Street, popped into the scene. "I heard the commotion about a 'rat,'" he said, "But I'll do what I can to take care of him. When I can't, then you'll have to, Mrs. Judson."
The housekeeper nodded gravely in agreement.
That very night, Fidget tried to sleep hanging upside down, though it may be tough to do when people that were close to you died. Taking a deep breath, he finally fell into a deep sounding sleep.
A month later, Fidget was no longer scared of the rat who put his parents to death, but was still discouraged about his loving parent's death. He missed them so much. Just then, a hint of confidence rushed in. Staring up at the ceiling, he thought, Maybe they're looking down upon me from Heaven.
"Penny for your thoughts?" Basil asked as he stepped into the living room.
"Mr. Basil, I'll have to confess that I'm not afraid of the rat who executed my parents, anymore," Fidget stated, "That's why I'd like to have a talk with him."
"I don't know, that could be risky," said Basil, overprotectively and strictly.
At Basil's sternness and patronization, Fidget became very offended and snapped, "I'm old enough to know that stuff!"
"Fidget, what has been getting into you today?" Basil asked, alarmed by his different behavior.
"Look, I've dealt with them before," Fidget demonstrated, "First, I've gotten a peg leg that replaced my left leg when I was little on the day I was following my bouncy ball down the river and my leg was chewed by leaches. Next, I broke my wing by mistake when I fell."
"I see your concern," Basil tried to say.
"Apparently, you don't!" Fidget retorted, "You're just treating me like a little kid by telling me stuff that I already know. I'm well aware of the dangers, although I don't care what they are, you rat and traitor!"
Basil was torn by Fidget's insults. "I'm sorry you feel that way. I'll try to let you have time to cool off. By the way, I'm not a rat."
"Please do! Besides, I'm old enough to be by myself anyway and no thanks to you! Oh, and maybe you are a rat, Basil of Faker Freak. Now, leave me alone." With that nerve, a headstrong Fidget ran away with Basil being shocked, but speechless.
Moments later, Fidget came to a dark, dank sewer, where he met a vile sewer rat that massacred his parents. The rat stood out from the sewer, and stopped the bat. "What seems to be the trouble, young lad?" Ratigan inquired, "Where are you running to in such a hurry?"
"It's Basil, he's so annoying and overprotective which is why I want to move out," Fidget explained.
"I see, I don't like him, either," Ratigan said, "He was the one who messed up my schemes!"
Fidget shrugged his shoulders, saying, "I never thought of it that way, actually."
Thoughtfully, the rat offered, "If you're interested, I can take you in, but first, I have to put my nice clothes and shoes on."
To this, Fidget only hesitated. He had every right to. After all, Ratigan did kill off his parents. Giving in, Fidget nodded as soon as Ratigan came back and Ratigan gave him a hug and let him in. "You must have had a long day and have nowhere else to go," surmised Ratigan, "Why don't you rest in here?"
As a few years rolled by, Ratigan got to know Fidget and had him commit crimes like stealing the Flavershams' uniforms from the toyshop, and the detective who had outwitted the rat for many years.
At the toyshop where Fidget had watched Basil tumble down from above the ceiling, laughed at his sufferings. Ineffably, Fidget taught Basil a lesson for shutting out kids (including older preteens like Olivia, who was ten years old) who feel responsible for their parent's abduction. As an example, Fidget seized Olivia, who was only meant well to both Basil and Dawson. In his mind, when that happened and on the same day Basil had been caught in Ratigan's sewer, Fidget thought words against him like, "You know something, Basil? Although Ratigan is nothing but a sewer rat, he was right about one thing: The only person you ever thought about was yourself. Oh, and one more thing, I never wanted to make the same choices as Ratigan did." Maybe Fidget was just as tough, feisty, and defiant, as Olivia because of those things than he had anticipated. To put it in another way, they both have attitude and were blamed for many things. Although they show respect for their elders, there are exceptions to every rule.
That very night, when Fidget had decided that working for that rat put a negative effect on him, due to the fact that he was nearly fed to Ratigan's cat, Felicia, as a result of Fidget's abuse, he finally defied the callous, evil rat. Aside Ratigan's cat, Ratigan also willfully lied and tricked Fidget. That meant Ratigan, too was treating him like a child as if Ratigan didn't want him to know the truth. Sure, Ratigan had friends in high places and seemed to have successfully lowered Fidget's self-esteem, but he never asked individuals of Mousedom to change who they are for him, including Fidget, not even if the rat wanted to, he couldn't because it's downright pointless. Considering that, Ratigan couldn't control Fidget's or anyone's destiny for that matter because Ratigan mainly puts his energy in obsessing over himself as if he were the popular one.
After a while of putting up with it, Fidget finally cut to the chase and started confronting him before plunging into the Thames River because it was natural and normal for him to feel this way; on the contrary, all the rat ever showed and granted him was condemnation and disdain. For an average intelligent bat, it was obviously hard exhaust him to waste because he is not a little boy anymore. Mocking him seemed like fun for Ratigan, but the rat never fully understood Fidget or anyone because Ratigan wasted a lot of time with someone like him and that the rat wasn't easy to get along with. Not even when Fidget got everything off the stupid list, despite the fact that he dropped it in the toy store. Because Fidget was all grown up, he no longer needed help from that rat who thought he was perfect and never cared about him or anybody other than himself.
That very evening, Fidget had fearlessly heaved himself from the Thames River to keep himself alive and as he ambled through the streets, he took a careful glimpse at his left wing. It had been healed before his eyes! I did this for you, mother and father, Fidget thought. With that thought, he dove inside the sewer where Ratigan once lived. No one seems to be here, he contemplated. In the darkness glinted a lit torch. Fidget grasped it and burned Ratigan's house when it was no longer in use.
Lastly, he hastened to apologize to the Flavershams, Dawson, Basil, and the Queen for their abduction. Eventually, he was forgiven and Basil had atoned with Fidget for his patronizing actions. As soon as Fidget regarded it, he forgave the overprotective detective and London was finally safe with Ratigan gone for good.
Oofta! I thought I'd get this one out of the way. Now, I have other theories:
*Perhaps, maybe Felicia had something to do with Fidget's broken wing and him getting a peg leg when Felicia bit off Fidget's left leg. Either that or he was chasing down a frog or butterfly curiously in toward the lake, which led him to his downfall- his left leg eaten up by leaches. Otherwise, Fidget was born with a birth defect for one of his legs and his doctors provided him a peg leg.
*In the climax, though Fidget is brave whenever he needs to be, he seems capable of making his own decisions and taking care of himself, without him having to take rubbish from anyone else, especially not from Ratigan. Speaking of which, I thought an enraged Fidget bravely stood up to Ratigan and calling him out on his hatefulness by voicing his furiosity, "No! Not me! I can't fly! I can't fly!" This could mean Fidget had been describing that he was sick and tired of being bossed around by some sewer rat, Ratigan keeping secrets from him, and blaming him for everything. It could also indicate that Fidget had lost innocence by seeing who Ratigan really was and Fidget getting the last word in an argument. Besides, the bat doesn't care what it can lead to.
*Likewise, Fidget doesn't apologize to his captor and/or offender because he'd have a blank expression on his face because it's unfair, he's much smarter and better than that, and he'd realize that in his heart, the offender or captor should be sorry either way. Similarly, if Ratigan did begin caring about Fidget, Fidget will not ever forgive him because Ratigan went too far. Forgiving people who aren't sorry for their misdoings is not the type of person Fidget is. Sure enough, the only time Ratigan was ever sorry was when he got caught.
*Maybe Fidget thought about moving out away from Ratigan when he grew older and told him about it. Ratigan would have been rubbed off on it, but would have come to terms with it, anyway. Then, the bat would have smiled about it and where he moves is none of Ratigan's concern because Ratigan helped enough. Ratigan is similar to Mother Gothel from Tangled and Judge Claud Frollo from The Hunchback of Notre Dame because of it. Besides, moving out and running away are two different things.
*Furthermore, the scene where Fidget thought words against Basil, he was calling the detective out on his hypocrisy, selfishness, bitterness, and narcissism.
*Interestingly enough, the way Ratigan said to Basil on top of Big Ben, "There's no escaping this time, Basil," he must have had the psychotic tone in the process of killing of Fidget's parents without remorse whatsoever. If not, maybe Fidget's parents got lost and Fidget tried very hard in vain to search for them. If he couldn't find them, he'd call them because he may actually still have their phone number in his wing pocket. That way, he can reach them by phone whenever he likes.
*Curiously enough, I mused over bats taking a liking to peek-a-boo.
*One other thing, a baby bat is called a "pup".
Generally speaking, I was mulling about what I think Fidget was like back then.