Tara and Alicia, while they consider each other sisters, aren’t related by blood, nor is their father their biological father.
They first met in ”Home for troubled young”, as they were left there around the same time in their early teens. Alicia is couple years older than Tara, but they quickly became friends, as being older than many others there, they found connection in each other. The exact reasoning for why they were brought there by their biological parents is bit different for each, but it can be summarized for both of them as: lack of respect for authority, and tendency to cause trouble.

Due to their older age, and having already learned to manipulate others a bit, the two managed to get slightly better treatment than many others in the institution, though they still weren’t safe from the worst parts of the place, and in some aspects, due to being older, they actually had it worse. They however weren't there for long, as only few years from their arrival, the place burned down, so its impact to them remained minimal, besides of course meeting each other. 

The biggest impact to them came from what happened after the fire, as in the chaotic aftermath of suddenly needing to house a bunch of ”Troubled” young creatures, Tara and Alicia got selected into the ”sane” group, which was pushed into the adoption system due to limited space in the alternative institutions. They didn’t really expect much, they knew they weren’t exactly on the top of demand after all, they still didn’t respect authority and their criminal history wasn’t kept a secret, so it was unlikely anyone wanted to adopt them. It didn't bother them though, as they frankly didn't want to be adopted, they were old enough to care for themselves, what did they need adults for?

However, it didn’t take long until someone got interested in them, they overheard older male feline asking about them, and after hearing everything, and regardless of being recommended many others, he came to see them. He seemed wealthy, and as he asked bunch of usual questions, questions to which the two answered with expected disrespect, Tara stole his wallet, seemingly unnoticed. As the potential adopter left, Tara and Alicia assumed that was that, but to their surprise, they had been adopted the next day.

They weren't really given any choice, as the orphanage where they had stayed quite literally pushed them out, almost as if they were happy to get rid of them. They were brought to a mansion, and they were excited; until they were told that they had to give the wallet back and apologize before they were let inside, and then had a door shut in their face and locked, in middle of winter, without proper clothing. To many creatures this wouldn't have been that big of a problem, but the two had short fur, and they were not build for cold weather.

Needless to say, they swallowed their pride and apologized. 

After they had settled in, they of course kept challenging their new "father", not having gotten the message from their first day, but it only lasted for few weeks, as they were provided with a crash course on respect. In summary, the first day was a taste, and the few weeks of defiance followed a similar course; Their to be father never touched them, and they were never actually harmed, but they learned their place. They think back to that time positively, as while unpleasant experience, they were ultimately happy that they did accept their place, due to what they gained from it.

When they started respecting him, genuinely, rather than out of fear for punishment, he respected them back, and he wasn’t actually that strict, or strict at all really, he only expected basic respect towards himself, and the willingness to do as told; otherwise they were free to do pretty much anything they wanted. After the first few weeks, they never saw another punishment, even when they actively challenged their father, though they still apologized when they were in the wrong, and in turn, they got an apology when they weren't.

Their lives were great from that point on, their adoptive father was wealthy and influential feline, having his claws in lot of places both legal and illegal, and they had full access to all of that privilege. They were very much spoiled, and the few awful weeks were quickly forgotten. 

Soon their father brought them into the know, teaching them things and showing them around, they were as good as biological daughters to him, and soon enough they too saw him as their father. Along all of this, the two sisters had access to material and means to educate themselves on any topic they could imagine, and they took full advantage of that.

With such wealth and privilege, they soon started act a part, both in good and bad, they were educated and knew how to behave properly, but they were also prideful; and with them taking part in the various operations their father had his claws in, they indirectly, and in some cases directly, exploited those lot less privileged than them, and just in general started to treat those lesser than them like...well, like they were lesser than them. With this came more sinister side too, as they took glee in the misfortune of those lesser than them, and started purposely causing such misfortune, just for fun. 

However, then their father died, the cause was natural, and something they had known was long time coming, yet they felt it was still too soon. They inherited everything, but they didn’t celebrate, as even if they didn't share blood, he was their father. They kept a brave face at the funeral, which was a big event, but after it, grief-stricken from the loss, they isolated themselves for a while.

After grieving properly, they took full control of their father’s operations, though along it, they started a new hobby, kidnapping. They would take individuals, bring them to their mansion, ”have fun” with them, and then let them go, most of the time. They were of course smart about this, making sure that either the victim wouldn't know who they were in the first place, or that they wouldn't talk; not that it mattered much, as due to having their claws pretty much everywhere that matters, they were quite untouchable.