???? New kittens ????

Hey loves!

I just got two new kittens, I had first gotten Luna and then we got Nala. At first Luna would have nothing to do with her but now they eat together, cuddle together and play. How ever when it comes to play some times Luna can be very vicious, but I’m not sure if she’s being vicious or playing aggressively….but either way when she gets like that Nala screams like she’s being murdered. Is this normal? How can I get that part to stop? She’s not aggressive with her plays just som times, and they play A LOT!