New kitten-old cat is hiding?

Ok so is this normal?
I brought home Oliver's new companion yesterday. She is a 7week old calico kitten. I brought her up to him and he hissed and walked away. She could care less about him. Now, keep in mind that up until this, he's always been a big scaredy cat and will hide a lot. Stella (the new baby) is locked in her own room with all of her things. Oliver's been in hiding since yesterday even though he has access to everywhere else in the house. Should I be concerned?
Second part of the question- I feel terrible leaving Stella locked in the room alone at night. She's fine right? I'm doing this right? Please advise.....
She cried for a few minutes last night until I brought her a stuffed tiger. Apparently she liked that because she was quiet for the rest of the night.
Thanks!

the way i've introduced the last four kittens in my house is pretty simple. i let the kitten and adult cat get to know each other.(with the exception of the first kitten i brought in 5 yrs ago, when i didn't know any better). i think i've shared this story on this site somewhere.

either way. take the kitten out of the room you have her locked in and let her roam the house. she'll encounter Oliver and they'll likely hiss at each other and posture and fluff. Oliver will not hurt her. he may take a swipe at her but it's just his way of saying 'i'm the boss here!' they need to establish the pecking order. keeping the kitten locked away is just going to make it more stressful on both of them.

example: last kitten i brought into my house was Elly (last month). i just let her wander around, encounter the other cats and explore her new digs. she had 4 adult cats to condend with and none of them have caused her any harm what-so-ever. fluffing and hissing and the odd growl. even the one that's most opposed to her, Lilly, has been caught on camera having a great old snuggle sleep with her.

just make sure to give Oliver extra cuddle time so he knows he's loved.

Thanks for the input. My only concern is that the kitten was a barn kitten so I'm trying to make sure she uses the litter box. She's been great since yesterday. No accidents - has used the box only. Now that she knows where the box is should I just let her go but keep an eye on her?
I will eventually be moving the box into the basement (where Oliver's is) but right now she's probably too little to climb the stairs. Suggestions for this?

leave the box where she can easily access it for now. once she masters the basement stairs, she'll find the other box.

yeah, just let her explore her new house and her new companion. like i said, there will be fluffing and growling and posturing. one big no-no though....don't force the kitten on Oliver. just let her go to him in her own time. Oliver will likely respond with his own curiosity. and supervising is always a good idea.

My Zoe can be a very moody little miss. When I bought Bella home, she hid for three or four days - she was mad with me for bringing in competition for my love!

I did keep them seperate the first day I left them home alone, however from day 2 they were together, and although Zoe hissed, spat, took a few swipes and was generally grumpy, they are now best friends and quite often lick each other and sleep all curled up together.

I know I was frightened to leave them alone together at first, fully grown cat and tiny little kitten, but kittens are made of tougher stuff than you think and grown cats will get over it (eventually!)

Good luck!

Everything I've read and all the advice I've gotten says to keep them apart for at least 7 days. They will smell each other and get used to each other, and SUPPOSEDLY not have the trauma that sometimes happens. People here seem to have had good luck just putting them together, but I'm on day 4 of having them apart, and crossing my fingers - I love my older kitty so much it's hard to see her as upset as she IS over this. She did get a look at him on day #1, and hissed & growled, then hid for the day. I think there's a million ways to do this, and I wish you luck with your kitties!

I've been doing a little of both. I let Stella out to wander and investigate the house when I'm home only. She's run into Oliver a couple of times and he just hisses at her and runs away. I don't really see any aggressive tendencies.. it looks like more fear. I suppose he thinks that Stella is a monstor in a kitten costume?

Anyway, Stella sleeps in her little room at night and stays there during the day so that Oliver still has the run of the house. Oliver gets special attention when I get home before Stella is even let out. I'm trying very hard to show him that he's still #1 in my life, he just has to share me now. Oliver gets to sleep with me for now and eventually hopefully they both will.

I'll keep you posted. I really want to make this work!

Guess what... they spent at least 10 minutes in the same room this morning! Stella would try to approach Oliver and he would hiss and she would back off. But at least Oliver isn't hiding anymore... I'm hoping this means progress!