I got a pair of baby rats around two months ago and they are now around 3 months old. I've been trying intros for about two weeks now and while they're doing great with one of my boys the other one is not so good. He's not been necessarily aggressive but he's a larger rat and had freaked the babies a bit the first time they met. He doesn't immediately attack them when put in together but will sniff them a lot which leads to squeaks from the babies (I don't think they are getting hurt, no cuts on either but more so being scared of him). He's tussled with one of them a little bit but it's the same amount of fighting I saw when I introduced him to my oldest boy. The babies will huddle in the corner together when he gets too close and if he ends up next to them they will jump out of the pen and I can't get them to stay in after they've been freaked. Is there anything I can try to lessen their fearfulness of the older boy? Currently, they are meeting in a playpen a couple of meters away from both their cages (Each pair is in one half of the dcn) so could it be a territory issue with them needing to meet farther away from the cages?