I have had a female guinea pig named Macy for nearly two years, I got her by herself because my parents only let me get one at the time. Recently I got a baby guinea pig (female as well) and she is only two months. I was expecting it to be a bit difficult with Macy as she's been alone for so long but the only way Penelope leaves the corner is if Macy is out and about as well. Macy has been aggressive (I am very sensitive when it comes to animals so I could be exaggerating). She has been doing some ear nibbles which I know is a dominance thing but she does it repeatedly until the baby squeaks rather loudly, and even then, no one moves. Penelope will only occasionally run but when she does, Macy runs after her. When we first introduced them, they were being held (it was like two seconds) and Macy couldn't care less. Then we put them in the bathroom with a divider and Macy didn't care. We moved the divider and Macy didn't care and would only jump a bit if Penelope smelled her. Then I moved them into a cage (3.5 x 2 grids) and immediately Macy was being more aggressive. I get that it's her territory but when I'm woken up by squeaking or loud running and look over to see Macy chasing Penelope, I worry. Last night, I split the cage to let them see/smell/hear eachother as well as give Penelope time to mark some territory herself but Macy had gotten under and below the barrier. Now the only problem is Penelope gets even more anxious if Macy gets too close sometimes (she's a bit more alert around Macy) and considering Penelope is scared I can't help but think I'm doing something wrong. Is all this normal for a few days and should I stop it or let them sort out their hierarchy?