Get littermates – zero mutual adjustment time.
We can try, but we want to get them from a shelter and we want a little bit older than kitten age so it may not work out that way.
I went for kittens despite my fear that they’d be too rowdy (I’m gone about 12 hours a day) – turns out they take out a lot of their energy on each other, not on my possessions.
ETA: of course, if you adopt them both from the pound at the same time, the staff should be able to help you find two who are known to get along together.
There are often two brought into the shelter together who might really want to stay together - you taking both would probably be a boon for the shelter (and the kitties).
My two girls have been together for about six years now, and the slapfights and hissing never end (but neither is hurt much by it - just the usual scratches). One time when there was another cat outside bothering them (they’re inside kitties), they truly went off on each other - you will absolutely know it if your cats are trying to do serious damage to each other.
If you do have to separate them, get a broom or mop - don’t get your own skin involved in it.
Oh. I had intended to just use the spray bottle if I needed to use anything at all.
I don’t think the spray bottle would be enough - sometimes you have to physically make one cat go one way and the other go the other way. Without losing all the skin on your arms. Like I said, if they’re truly going at it, they are just little wild animals - they don’t know or care about you.
My roommate and I just got cats and there is plenty of hissing involved. Sometimes skirmishes, but never bloodshed. If one of us raises our voice it breaks up on its own. For the most part we let them tussle a bit. After a couple weeks they seem to be more tolerant of each other, and sometimes sleep next to each other as well. Although they still hiss at each other during the day. Baby steps, I suppose.
Depends on the cats. Mine will go at it like bloody murder, but the instant I shout, “Yo, cats! Break it up!” they both sit up and do their I’m an innocent little kitty act.
So far, raised voices have no impact at all on my cats. My 7-year-old daughter will walk into the kitchen where they’re fighting and yell, “Boys, boys, break it up! What do you think this is? A kickboxing ring?” 
They don’t pay any attention to her, though.
Nekko looks just like my Bo who passed away last summer at age 17 - (my thread about him). Gotta love those flame points with blue eyes.
I have a 5 year old tabby and a almost 2 year old tortie who wrestle a lot. They are usually either wrestling or snuggling.
I use canned air instead of water - my cats react to it better (sometimes with water they just sit and stare at me) and my stuff stays dry.
My two are best friends but they wrestle pretty much constantly. Neither is 2 years old yet. As long as I only hear furry bodies hitting the floor, I’ll let them go at it. On the super rare occasion that one of them begins hissing, I’ll break it up by walking heavily towards them. They usually clear the room fast and go hide together. For about 30 seconds. Then they’re friends again. Hah!
You might want to close Neko up in a bedroom occasionally and give Ponch a break and maybe even a little treat.
What a wonderful idea! I’ll have to try this!
We do this. Ponch is allowed to sleep in my room with me, for instance; Neko is not because he will walk on me in the middle of the night and wake me up. Also, Ponch (as an adult) is allowed to go down the basement (I’m pretty sure there are mice down there); Neko is not allowed down the basement yet. Sometimes when Ponch wants to go down the basement, I’m pretty sure he just wants a break from Neko.
Compressed air works well, but it’s not advisable. If just the sound scares the cats off, well and good, but pointing the nozzle directly at a cat causes a couple problems. Since it’s not actually air in the can, there’s a potential for toxicity (that Wiki page notes it’s an abusable inhalant, but beyond that I don’t have a strong cite), and if some of the liquid sprays out and hits skin, it can cause damage since it’s so bloody cold.
I never spray it directly at the cats; I use it for the sound effect. At this point just bringing the can (no spraying needed) out deters them from doing whatever bad thing they’re about to do.
I guess mine are just a couple of wimps. As soon as I shout, “Hey, hey, break it up or I’ll break it up for you!”, they go from biting and clawing to kissing each other. It’s like they’re trying to fool me. No, Mom, you’ve got it all wrong. We’re just, uh, taking a bath. Yeah. A bath. That’s it.