introducing new kittens

Question
hi Karen,

i recently got a second kitten that is 7 weeks old. i think i introduce it to my current kitten too soon and now i am trying to make there interaction calm and peaceful. My current cat is 13 weeks old, timid and easily startled even by his own shadow and tail.
when there in the same room they seem to be okay, but after a bit the older one tackles the little one and starts to bite...the hissing and growling has decreased, but they can't be too long with each other...the little one is fine it minds its business but startles the older and then he starts to attack.
what I've tried so far was make there interaction fun, i played with them together at the same time, gave them treats together, took naps together and it would be okay in the beginning...i did notice that the older one would start to sniff the little one for a bit, then clean him and the little one would be submissive but then he just starts to bite him...
i did put the older one in the little one separate room with his toys, he was okay no issues and they did use each others litters box and eat from the same bowl and i do give them there own attention even more for the older one...
when i put the little one in his own room the older kitten doesn't seem to mind him or is not curious with the room even if he starts to "meow"...he only gets curious when i go into the room he starts to cry and want to go inside.

please help me if you can, any info would be great.

thanks,

Answer
Hi Salah,

Their behavior is perfectly normal. They are curious about each other. And they are trying to figure out who is top cat. You are doing a great job introducing them to each other. The only thing they need now is a little time. In a few weeks they will be best buds. Good luck and take care.

Ciao, Karen