We had Linney for 6 years and she was VERY bossy! She occasionally would give a random neck bite to her cagemate just because she could, and woe to anyone who tried to drink before Linney! LOL! Some sows just feel the need to reinforce their dominance more often than others. I don't think her cagemates were particularly unhappy, though... they simply let Linney know that they knew she was the boss and things settled down promptly (and that 'shriek,' as awful as it sounds, is really just the subordinate pig letting the dominant pig know that they agree that they are the boss and are not challenging them. I heard it a LOT over the years that we had Linney! It doesn't mean that they are hurt or even particularly frightened, they are just demonstrated that they know that the boss is not them!) Since you are not seeing any actual fighting, I think you are just seeing normal dominance displays and that things should settle down (with periodic hormonal flareups!) once they establish the pecking order. As others have said, it's better to keep them together, as separating them between meetings forces them to begin again at square one every time you introduce them. I also think it's really important not to translate human emotions onto guinea pigs. Yes, they have emotional lives, but their needs are not the same as ours. So what may look cruel to us is, in fact, very normal to them. I've also sometimes felt bad for my more subordinate pig, but keep reminding myself that guinea pig society is a hierarchy and that they are actually happier knowing their rank in the hierarchy. I've also noticed that some pigs really like to be the boss, where other pigs have NO desire to be the boss at all! When Linney passed away, it left her cagemate, Sundae, who is a very submissive pig, on her own, and she was very lost without the leadership that Linney had been providing for her whole life. When we introduced a baby sow I thought that Sundae would finally get her day to be the head pig, but she immediately demonstrated that she was totally willing to be submissive to baby Hadley (who was about half her size and a third of her weight when we introduced them!) Sundae apparently just does not have it in her to boss anyone around. She is very content to be the follower. Hadley is the dominant pig of the pair, but you would never really know it... she's very mellow and not at all bossy. And Linney, as I've said, was the tyrant queen of all pigs in the household! LOL! But despite the differences, we did have several changing pairs with different personalities (Linney and Frenzy, Linney and Sundae, Sundae and Hadley) live together over the years and all seemed happy with the arrangement.