Introducing two kittens?

Anyone have advice on introducing two kittens? I have a approx. 14-16 week old kitten who I rescued as a stray at 5-6 weeks old. I think he was the only kitten in his litter.
My brother (whose apartment is upstairs) got a Maine Coon kitten recently, who is about 2-4 weeks younger than the other kitten but quite a bit smaller. We would like to introduce the kittens.

The problem is the Maine Coon kitten seems to be scared of the other animals in the house-- she will growl, hiss and arch her back. The stray rescued kitten also is a little bitey when playing, and will raise his paw and swing sometimes if another cat approaches him. Our resident cat is not helping his socialization with other cats because she really dislikes him and will hiss and swat him!

I'm not sure the best way to introduce the two kittens. I can't really have them introduced slowly on opposite sides of a door because neither kitten is allowed the run of the house yet so they are both usually in their own rooms on different floors.

In my experience a gap of 4 weeks is no problem when introducing kittens. The hissing and swatting are normal first encounter behavior. Supervise their first meeting, let them check each other out, have toys and treats for them for good behavior and hopefully they'll get along immediately.

Hi, I hope you dont mind me joining in this thread but I have a similar question and it seemed silly to start a new thread (found this forum looking for advice)
I have a 16 week old female (pipsi) who I've had for 8 weeks, a couple of days ago I got a 9 week old male (no name yet) the trouble is Pipsi doesn't seem too happy about her new companion, there was a lot of hissing and swatting on the first evening, they were kept apart that night and then the next morning I found out about the 'safe' room and have been using that, what I was wondering was if anyone has any extra advice about introducing two kittens, I'd love to get the little guy about the house as quick as possible as he adores company and it breaks my heart leaving him in there (no matter how many comforts I leave him with!)

Yours hopefully
Onyxx

When I bring in a new cat, aside from their normal 'quarenteen' period (if they are a rescue), I just introduce everyone, and let them establish themselves as they will. Because they are both kittens, they won't 'fight' so much as established adults may. They may scuffle a bit until roles are established, but other than that, they should be fine...I have found that it is best to try not to interfere.

I agree, just open the doors and let them 'discover' each other naturally. Unless there is blood or blood curdling screaming, they are fine. If you have to ask if they are fighting or playing--they're playing.

Thanks both of you, I'll give it a go She's quite a bit bigger than him at the moment but he's a fiesty, chunky little dude so it might be better to let her get the upper hand while she still can!
Think will still keep them apart when we're not here and at night - my wonderful husband is sleeping on a very uncomfortable sofa bed in the spare room with the new guy so he doesn't get lonely (Pipsi snuggles up to me every night and I didn't want to give her any genuine cause for jealousy)

Thanks again, this is a great forum