Update on Olly and Emma--Funny Story, and a question

So, as some of you know by now, we recently adopted a 10 mth old spayed female cat/kitten as a companion to our 3 yr old neutered male Oliver.

So, we had Emma in her own room, and she and Oliver were sniffing at each other through the door, and, generally, seemed relatively unperterbed by each other.
Well, Oliver has always been a little smarty pants. He's been known to turn on faucets, open doors, drawers, hide things, etc.
We assumed (and you know what happens when you assume) that he couldn't open her door--it's a french door w/ a lever type handle, which is much higher than normal door handles.

Well, apparently, he and Emma had other plans!
Emma had begun to be upset about being locked away--she could tell that there was much more house on the other side of the door.
And, apparently, she and Oliver arranged a jail break!
Turns out, if you lean on the door to the guest room with some force, you can pop it open! And since Oliver weighs over 12 lbs, it must have been easy for him!

Next thing we know, they're both zooming around the house--this happened at about 6 this morning.
Oliver has not hissed or shown any agression towards her, at all.
She will hiss at him occasionally or bat at him--I think she's just trying to test him--but for most of the day today they've been peacefully co-existing, most of the time in separate rooms--Oliver is still going through his daily routine, watching pigeons, begging for faucet water, etc.

I keep trying to put Emma back in her room but everytime I do, they both sit at the other side of the door and cry.

Should I just let them figure it out from here, since no one seems too upset?
Or since she's still swatting and hissing, should I stick her back in her room and ignore their sad cries?
I'm thinking, if they were going to battle it out, wouldn't they have already done it?

Anyways, any advice would be appreciated!

Guess your two decided to introduce themselves to each other and have also become partners in crime (LOL)!!!

Since they seem to be, as you say, peacefully coexisting, as long as you're around to keep an eye on them so things don't get out of hand, I would let them be around each other. Oliver sounds like he's adjusted beautifully to his new sister - what an easy-going boy he is! Emma's hissing and swatting is to be expected. Don't be surprised if they do "battle it out" : they may run after each other, bat at each other, etc. You just don't want things to escalate to biting and fur flying. I'd still separate them at night when you can't watch them or any time that you'll be out of the house.

Since Emma's warming up more slowly to Oliver, you might also want to try associating Oliver's presence with good things - a special treat for them both when they are near each other and behaving well.

Please keep us updated with progress reports!

Partners in crime, indeed. They sound good at it, too.
As long as they aren't actively hurting each other, I'd just let 'em have fun together. I've had a lot of cats over the years but never any that really just hated each other to the point where they did really nasty fighting - mainly just hissing and swatting and a bit of chasing, at least for the most part. You may want to keep an eye on them to make sure they don't get aggressive, but they sound like they are making friends nicely - always a good thing.

So far, so good! Emma seems to be trying to assert her dominance--her new favorite pastime is stealing his toys (even though she has her own brand new ones). Today they've been ignoring each other for the most part--Oliver's favorite place to nap is way up on top of our tv hutch--and Emma is too tiny to jump all the way up there--so at least some of his stuff is still sacred!
He wins the big brother of the year award--everytime she gets sassy with him, he just looks at her like "Seriously, why can't you just be nice to me?" No biting or scratching on either part--last night there was lots of chasing--which they both seemed to enjoy!

So, to get the full "back story" on my two cats, you can read the thread "update on Oliver and Emma" in this forum.

Anyways, Oliver and Emma have been together for about 4, 5 days now after they orchestrated Emma's "jailbreak". About 70% of the day they're fine, taking a nap, usually in the same room, or just hanging out, being cats.

About 30% of the day they decide to reenact movie chase scenes. Then, after about 5-10 mins of running around like a herd of buffalo, Emma gets perterbed and starts hissing and growling at him--I'm thinking he just doesn't know when to stop (typical male, huh?) I've been trying to let them figure it out themselves for the most part--we keep them separated when we're not at home to avoid any major catastrophes.
Do you think I should separate them when the hissing and growling starts? It's driving me batty!!! Plus, I don't want Emma to feel "threatened" by him--even though he's never hissed or growled, he is about 3 times her size so she might be intimidated.

What do you think?

I merged your threads because they were related and keeps the story together so that people understand what is happening.

Let the cats work this out themselves, they will. It doesn't sound to me like you have major issues with them. They are posturing and chasing and trying to figure out which one is going to be the head honcho.If you haven't had them go airborn in a fight, or roll together in a spitting clawing ball, you are likely just adding to the situation by getting stressed out. Keep a blanket nearby that you can toss on them if they start fighting. Stick a pair of earplugs in your ears, or put on classical music if the hissing and growling bothers you. But all of that is normal for two cats put together in a small space and being asked to coexist. If you haven't had to rush them to the vets, you are doing good with them.

Thanks Hissy!
Another quick question--another curious little thing Miss Emma has been doing is she seems to enjoy, how do I put this....licking Oliver's bum. Not licking him anywhere else, just the bum area. I've never seen this before...I'm guessing it's a good thing? Yes? Just seems a little...unusual...

It's common and called mutual grooming. As long as you know both the cats are parasite free, and you are treating them safely for fleas, I wouldn't worry about it. Yes we think it is nasty as humans, but in the cat world, it is how they identify with each other, and some cats just have a stronger instinct (usually the females). Now if she starts biting, you separate them, because that can be ugly if it goes on and gets into aggression-

Gotcha. I figured that was what it was--usually when I've seen cats groom each other, they've groomed all over, not just the, um, special spots. Maybe she's trying to tell him something!
They're both parasite free and she doesn't seem to do this aggressively--mostly she does it when they're in the sink drinking water together (even though they have a fancy water fountain Oliver just can't get enough faucet water) so I'm guessing it's a "bonding" thing.
Thanks