I have two chins, elvis and whiskey. I bought elvis first, he was alone in his cage at the shop or I would have bought a pair. I hoped after some work, elvis and my degus might be able to spend time together so he wasnt too alone, i couldnt get this to work and was worried about my degus as elvis was quite boisterous and a lot bigger then the degus.
Anyway i got another male chin around 9 months old (elvis will have been almost 2 years old) and introduced them on neutral ground with plenty of room to roam and they ignored each other initially. After a while they both 'kissed' but then started to go badly. Ever since, they dislike each other and although in different cages (next to each other) will try and attack each other through bars if one is allowed out.
I would love for them to be friends but im now stuck and dont know where to go from here
If they were degus we would recommend you put them out of sight, sound and smell of each other for a while so they can forget that they dislike each other, you won't get anywhere now until you can 'reset' their relationship. Then you would gradually bring the cages closer, then you could start swapping substrate and have the cages close up side by side and hopefully they would either be ignoring each other or showing signs of wanting to hang out together. Then you would try short neutral area meetings. You need to be prepared for it to take a long time.
This is still helpful to know as i also have two pairs of degus which were originally all together for months until a fight got too out of hand and resulted in bloody neck wounds so we were forced to split them. We could use this if we decide to try a reunion