Introducing Male Rats?

Heya everyone!
You might remember me from a couple of months ago, I’m a rat parent to two adorable little fuzzballs, Theo and Jamison, but my pack is slowly growing

Recently, I took a close friend’s rat whose companion had died, so he was all alone. I didn’t realise until I went to pick him up that she wasn’t really doing a great job at taking care of him and was actually pretty afraid of him, and admitted he’d bitten some people in the past, and said he was “cage aggressive” and grabby with his food.
All of this made me kind of worried, because my rats aren’t perfect, but they’re extremely sweet and gentle in every way possible. I was kind of worried these bad behaviours she claimed he had would rub off on my other guys. Nonetheless though, I took him in because she wasn’t doing the best job and he for sure deserved better and I knew I could provide it.

Which brings us to now! He’s been quarantined for over a week, and shows no signs of illness, and is actually an extremely gentle, sweet guy.
I had a little accident where I put him in a cage that I didn’t realise the bars were too spaced, and he escaped into the room he was being quarantined in, but my mom managed to catch him again and now they’re best friends haha. She pets his nose through the bars, and she claims he’s apparently extremely sweet and cuddly. She has been visiting him in my room a lot, which isn’t something she would usually do for my other babies! I’m just very glad to see how sweet and gentle he actually is.
He’s currently in a cage next to (but not too close!) my two “original” rats. I tried to really carefully examine their behaviour when both boys checked him out through the bars, but I’m not really sure what to think. They just seem very curious to me, but I know introducing males can present a challenge, and my Jamison is actually quite a bully to poor Theo.
I’ll upload some pictures later that will hopefully give you a better idea! I read you’re supposed to check if their fur is puffed and if they’re hissing or anything, but they just seemed to be sniffing and kind of grabbing through the bars.

In the midst of this, the same friend mentioned that she picked up two double rex boys for me, because she’s always know I love hairless/rex rats and never had the opportunity to get them. This poses a new problem, because while they’re apparently quite young (around a month and a half maybe) my boys are ALREADY in the process of meeting a new stranger. Should I stop introducing the first boy, and try to integrate the babies while they’re young, or should I wait??

I also want to mention that my partner and I had a really messy break up about a month ago. I don’t think it’s affected their cleaning/feeding schedule too much, but I’m worried it has affected them in some way, because their favourite everything spot (a hammock) is now being shredded. Is this just a normal “rats chew things” or should I be worried since something traumatic happened to me and it could potentially affect them??

Anyways, thanks for reading all of this, and thank you so much for any feedback!!

Hi Congrats on the new additions ..... looking forward to lots of pics

The babies will need to be at least 8 weeks old - 10 weeks is better, before you start physical introductions

Here is some info on introing rats http://www.ratshackforum.com/forum/showthread.php?t=32368
and joinrats.com has a lot of good information as well

How wonderful of you to take on that lone boy. And how sweet of your mom to have bonded with him. I'm sure that made the new little guy feel so much more secure.

So with the new babies, I would wait like SQ said until they are at least 8 weeks old. So in the meantime you can continue the new guy and your guys. And then add the babies.
It's best to do intros in a neutral area with no rat smells. A lot of people like to use the bathtub because it's confined and safe. I prefer to use a table top so they are at my level and I can be part of the process. Have a towel ready to throw on them should there be a rat ball fight. Just because they fight doesn't mean it's the end of friendship for them. They just need to keep seeing each other. How old are the three?

Thank you both, and I’ll for sure try to upload some pictures when they’re all settled!
I’d completely forgotten the babies needed to be a specific age, I was so worried about introducing them. But I’ll for sure be keeping them separate for about another month then, since I’m not entirely sure of their age.

Thank you! He really is a sweet boy, and I was a bit apprehensive about taking him in, but I feel a lot better about it. He’s still kind of scared but coming around. And he was in pretty bad conditions, so I’m so happy to see him doing well. It was also super interesting to see my mom bond to him so quickly, because she was pretty upset when he got out haha! She’s also never been extremely interested in my rats.

Since the babies have a little while longer before they can be integrated, I’ll go ahead and try to get Ben, the new guy, on good terms with my other babies. My boys are..... About eight months old now, and my friend said Ben is about a year old.

I also wanted to ask, does it seem like a good idea to section off part of the main cage and move Ben in? I have a Prevue Fiesty Ferret cage (http://https://www.petsmart.com/small-pet/cages-habitats-and-hutches/cages/prevue-feisty-ferret-home-14556.html?cgid=600124) which has a door that can close off the top from the bottom section. I also wanted to mention that none of the floor in my cage are wire, they’re all covered!
I was thinking maybe it would be a good idea though to have Ben on the bottom level and Jamie + Theo, so they’re close enough to smell/get used to each other. That means that all that’s between them is a wire door though, and I wouldn’t want to risk injuries in case somebody bites somebody else or gets too aggressive.

It is good for them to get used to one another's smell but necessary that they be out of reach of one another because they will bite through the cage bars. ........ so keeping unfamiliar rats above and below one another is not a good idea because feet, toes & tails are in danger ..... if tails drop through the bars the rats below will bite (and possibly amputate) them

There is a risk like SQ mentions, especially since the bar spacing on the Feisty is a bit larger. But if you take your two boys out to play by themselves, go ahead and put Ben in there to explore for a bit. Don't forget to remove him before you put your boys back in.

Ahhh, I can’t believe I didn’t think of that!
Since they’ve been sitting next to each other for almost a week at this point, I was going to go ahead and throw them in the tub together. I’ve gotta admit though, while my boys are sweet, no matter how much I play with them they still don’t like coming out of the cage. Do you think this means I’ve done something wrong?
I did also want to mention. I know sneezing can be a sign of something bad, but from what I’ve observed, it seems like all of them I think have been doing it. Jamie had a little bit of a sneeze that I was keeping an eye on, and everybody is being/has been quarantined for the recommended amount of time. Does this sound like an issue?

Every rat is different and some like coming out while others don't and even then, it could take a few months and they start liking it. I've noticed that with mine, they enjoyed out time more only if their cage was available to them to run back in and out as they please.

For the sneezing... it could be your rats are over sniffing the air right now because of the new rats and that in itself can cause sneezes. But keep listening to them and put their bodies to your ear to listen to their lungs. If you hear wheezing, grunts and clicks, then it's time for a vet visit.