How much growling/hissing is normal between two cats at this stage?

Hi all,

So - I introduced 6 months old male kitten to my 8 months old female kitten.

I did the introduction with isolation - maybe a quite speedy version because they were very friendly to each other within days - trilling and playing through the 1cm gap between door and wall.

He is here for over 2 weeks now, they chase each other, wrestle-play with each other (very delicately), trill to each other, lick each other, SOMETIMES (rarely) sleep together, eat next to each other and generally aren't really aggressive towards each other 99% of the time.

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The only issue is that when there is ONE toy the both want or ONE place to sleep they both currently want it or ONE food piece between them the resident kitty will growl or hiss and slap the new kitty then proceed to walk away all high and mighty. The new kitten doesn't seem to care at all and still goes for the toy/food/whatever as if it didn't happen or rarely also walks away.

I take care to avoid these situations with food, but with toys and sleeping place it will happen 2-3 times a day as the toys are lying around and new kitten seems keen to sleep with resident kitty and resident kitty doesn't seem to be happy about it at all :P

She probably wouldn't mind sleeping close to each other, but the new kitty tries to basically lie on her with half of his body and she never liked too much touching.

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Is this normal like - setting the rules between them - thing or should I somehow stop this behaviour?

Is this normal that the younger kitten doesn't seem to care at all and ignores the warnings resident kitty sends?

Will it stop in the future or is this just normal cat thing that will continue forever?