I've had my chinchilla, E, for about 4 years now and he's 7.5 years old approximately. He used to have a cagemate who died around 2 years ago (they had been paired for almost their entire lives.) So for the past 2 years we've bonded a lot more but I feel like he's lonely because I've been really busy with school and whatnot. So, I got another chinchilla, now named F, who is 9 months old, from a local breeder. I had ordered a cage online but amazon failed me (ordered the cage and 2 weeks later they told me they hadn't shipped it.) Not to worry, I brought my large, outdoor cage inside and placed both chinchillas in separate cages and placed the cages beside each other. I left them beside each other for around 4 days and then decided to try to cage swap, mostly because F seemed to have trouble jumping and the cage E was in had ledges closer together. So they stayed swapped and really for about a week I've been switching them out. Then, after about a week I brought them into the bathroom to interact and it didn't go well. There was chasing, teeth-showing, barking, mounting, snipping, etc. mostly provoked by E. I held them both close to each other and they chattered and showed their teeth some more. After a few more days I gave them both a dust bath back in the bathroom. E didn't seem so dominant anymore, trying to smell F but nothing more. Whenever E is near F, F freaks out, running circles and grunting and peeing. I don't know how to get him to calm down like E has. I put them in the same cage and F huddles into a corner, and E hops up to him for a smell and F jumps about 2 laps around the cage, jumping on E on his way around which stirs up E a little so E chases him a little and then they're both just running from or chasing each other. Should I stop F when he starts to run around? (probably won't be able to, he's pretty good with jumping now) or what? They are fine in the same cage when E is on the flying saucer (or on the thing underneath that connects it to the wall, even with F directly underneath) or when F is in his house. However, when F is in his house and E comes around to check him out, F gets very defensive and grunts more. What should I do? I've read lots about introducing chinchillas but it seems lots easier when you're not trying to do it yourself.