Hi, and welcome to TCS! You'll love it here...for many of us, these forums are somewhat of...well...an obsession!
Never will you find a more knowledgeable, friendlier, cat-loving community!
I'm just going to say that both of your new furkids are lovely!
Frenchie looks like a solid, fluffy, big girl who will EVENTUALLY give you a lot of joy and happiness...she just probably will need plenty of time to adjust and come into her own, so to speak. Tara is a youngin'...believe me, they tend to adjust far more readily to change, and accept other felines more easily than an adult cat. This is part of her appeal, as she seems to be taking her new lifestyle with you without a lot of hassle...that's the older kitten way!
I would venture to guess that Princess Frenchie hasn't been dealt an easy hand in life so far. She may have been neglected, abandoned, or put in some frightening scenarios in her 2 years of life. For many adult cats, being in a shelter situation can be traumatic, stressful, and scary. Can you imagine how you would have felt as a young child if your parents all of the sudden decided to either abandon you, or send you to a foreign place where you knew no one...or if that place offered you for the first time a warm place to sleep, new smells, different noises, and you just couldn't seem to understand why this was happening? Well, this is the story for most cats in shelters. And then, suddenly, some person comes along, and takes you (with a rather boisterous and unsavory younger child) to a place where there are yet again new sounds, new sights, new smells...oh! And this younger child won't leave me alone long enough to process and and get used to these new surroundings! I think you see where this is going...
Cats are creatures of habit. They don't like change, and it can create a lot of turmoil for them when their normal routines and environment are disrupted in some way. A lot of them seem aloof to us when we bring them home...and many remain in hiding (because hey, it's scary out from underneath that bed!!!) for a few weeks! And then we as their new owners start to wonder...what's wrong with this cat? Why won't she play with me? Why won't she let me hold her or sit on my lap? Why all of this hissiness with the other newcomer?
The answer is time and a lot of patience. Princess Frenchie has a lot of new things to adapt to, and this will take a lot of time. Give her several weeks, if not months...you will notice that if you introduce her to Tara slowly, and gradually, and allow her to investigate your home in small "bites" rather than allowing her free reign all at once, she'll be able to adapt more happily. It's going to take quite a while before you really see Frenchie's personality start to shine...she's too busy trying to get used to these changes, and she's stressed! Once she starts to feel comfortable, she'll thank you in her own way for allowing her the extra time to show you that she deserves a place in your home with her. She may even surprise you, and learn that she actually enjoys the company of Tara. I would venture so far as to say that with enough time, you'll grow to LOVE Frenchie, and learn to appreciate all of her little quirks and qualities.
I have 3 cats...two males, and one female. I added Ripley (the female...she was a kitten) to my household when my older male turned a year old...he HATED her for like three months!!! But, after a while, they started to sleep together, and even play with each other. Now, Fergus is 5, and Ripley is about to turn 4, and they are the best of friends. Now, last year, I added the other male, Captain Steuben. He was just 8 weeks old. Both Fergus and Ripley despised him. And we all gave Steuben time...now that he's turned a year old this month, Fergus, Ripley, and Steuben are living in harmony, and all seem to be friends.
Time is the key.