rat cyst...?

Question
I have some questions about my rats. Only the cyst question is important right now.  The rest is just background, and some curiosity about my adult rat.

Here is some background which may/may not be relevant:

I have two male rats who share a large cage.  About three months ago, I adopted them from the same place, and chose them because they seemed to like each other.  They are probably four to six months old, possibly a little younger.  Banksy (black and white hooded) has always been very social and hyperactive, bounding around like a puppy, but he is dominant.  

My submissive white and tan rat Kingsley started out very scared of people, and would empty his bowels all over anyone who held him.  After  trust training him, he became very sweet and his timidity seemed to pass.  However, when he came down with a minor upper respiratory infection, I had to force feed him antibiotics with a dropper.  His infection cleared right up. Though I never actually hurt him, he stopped coming out of the cage to me, and no one else can touch him at all.  He became much less willing to move around, staying mostly in his tunnel.  He's gotten kind of chubby, and eats much more now. I'm not sure if I should worry about that, but he was much smaller than banksy up until recently, and now he is much chubbier.  They fight sometimes, and Banksy picks on Kingsley, but it's never really seemed out of hand.  They'll fight and squeak for a while, then the next minute they'll be sleeping on each other.  

****My primary source of concern is what happened last night when I got home.  I had played with them both that morning, and everything seemed very normal.  My boyfriend, who was ratsitting, told me that he thought Kingsley had a cyst on his head a bit behind his right ear.  He planned to show it to me when I came home, but when he left the room and came back, he noticed that Kingsley was bleeding a lot from the abscess.  He said that it was oozing very yellow fluid and blood, and that it appeared as if one of two things had happened:
1)Banksy groomed him and burst it (because Banksy kept trying to groom Kingsley when it was bleeding.  He did not seem dominant or violent, but wouldn't leave him alone).
2)Kingsley burst it against a sharp edge in the cage (there was blood and yellow fluid on the side of the cage)and/or scratched it himself.
He also speculated that Banksy may have bitten him and it became infected, causing inflammation, which I suppose is possible...but not in such a short amount of time.  

But when I returned home, Kingsley was bleeding a lot and bit my boyfriend (hard! breaking the skin! And neither baby has bitten anyone before!) when he tried to touch him.  Kingsley let me take him out and look at him.  The wound was relatively small, but bleeding a lot.  I applied pressure to it and cleaned it with peroxide (which I found out today was a mistake for rats!)  Kingsley was panicked and squirming, but he let me bathe him and hold him until the bleeding stopped.  He didn't seem to be in too much pain, and he did not manage to reopen/irritate the scab, though he wouldn't stop grooming himself.  

We put him in a separate cage and gave him some treats and played with him for a while and he seems just fine now.  The cyst did not swell overnight.  It is barely noticeable now.  The small animal vet is closed today, but we're going to secure an appointment asap.  In the meantime, I'd like to know your opinion on what this bump was and/or what caused it to show up in less than a day.  I understand that I should mix some saline solution up and use it to clean the scab?  Is there anything else I can do?  I have been home all day keeping a close watch on both rats, and I really want to do anything possible.  It hurts me so much when they are sick/hurt.

I have one additional question about my third rat Hannibal.  I don't really know how old he is, but he is pretty big with a very long tail.  He is perhaps a year old...give or take. He is completely black except for the white cuffs around his ankles and a long strip of white down his belly. Hannibal is very long and slender. He used to belong to my boyfriend's exroomate, who bought him as food for a rattlesnake (augh!!!).  However, when Hannibal was put in the cage with the snake, he fought back pretty hard.  When they removed him from the cage and put him back with his cagemates (an albino baby rat and another rat about Hanni's age), he disappeared into a corner of the cage and didn't come out for three days or so.  On the third or fourth day, my boyfriend came back to the horrific sight of Hannibal eating the albino next to the corpse of the other rat.  The roommate wanted to put Hanni to sleep, but my boyfriend couldn't stand for that to happen.  But Hannibal proved to be a very difficult pet.  He not only grabbed/attacked/bit ANYTHING that came near him, but mutilated anything he was given.  Both my exroommate and I experienced nerve damage from getting too close to Hanni.  No one has ever held Hannibal since the snake incident.  I became very attached to Hannibal when my boyfriend moved in with me, and he sort of became mine.  I played with him (without touching him) and fed him, and now he sometimes lets me pet him as he leans against the cage.  He's cool with me, but he still attacks everyone else, and doesn't seem okay with Banksy and Kingsley.  I wonder if you think there's any chance that I will ever be able to hold Hannibal.  I also wonder why Hannibal looks so different from my two other rats.  His front paws look very different than theirs, like little hands as opposed to their little claws.  He eats differently too.  They mostly like their rat food, but he hardly touches it, and waits for me to give him human food.  He builds these amazing forts out of newspapers, like nothing the babies have made, and he doesn't seem as nocturnal as they are.  The most striking difference is his crazy looking tail. The babies have short pink speckled worm tails with a scratchy texture.  Hanni's looks like it's covered in black lace. It's actually very pretty, and the texture is very interesting and intricate.  

ANYWAY
Thank you so much.  If you read this entire thing, then you're awesome.  And if you read part of it, you're still awesome.

Answer
Hi and thank you for being so detailed and YES I read the entire thing...if people read my mini novels I can certainly read a message that is detailed like I ask them to be, as yours was.

Lets start with Hannibal.  He needs neutered, badly.  Living a life without human touch has made him totally withdrawn and that is really no fun for him. He will be a new rat, I promise you this. I also suspect he is  wild hybrid. Is his tail longer than normal and does he have a bit of a point to his snout and are his eyes more slanted? The way you describe his feet remind me of my wild rat, Holly, who I had for nearly 4 years and she was a real maniac.  Hannibal put up a fight with that snake, which is not really totally unusual but to basically WIN by not being eaten....let me ask, did he hurt the poor snake?  Who in the heck has a rattle snake? I Hope he is defanged. We refuse venomous snakes and snakes that are fed live at our clinic basically because there is no reason to feed live in captivity.  The snake could be hurt too, from a rat like Hannibal.   I would seriously neuter him. I would be sure the vet you take him to is an exotic vet with PLENTY of experience with rat neuters etc...and just do it. You will be so happy you did!!  I have had lab rats that were poked and probed and hated humans and I regret not having them done but at the time I had 23 rats and did not want to pay to neuter four rats because they bit me. They loved each other and at least they had that much. Hannibal has nobody.  I read a story sort of like this a few months ago...on here to be exact, and this guy wrote and refereed to the rat that his snake did not eat as an "IT" because he could never touch her to see what sex  she was. She was near 2 years old I think and this rat was so nuts because of the trauma she went through surviving a snake attack that she was mean. I figured out she was female when he described  that something was coming out of her...which told me she had uterine prolapse.  I felt bad for the little rat not being touched or loved for 2 years.  I could tell you how to trust train him like I did Holly, but how old is he and how long have you had him?  Spaying would not help an aggressive female but again, neutering works miracles on aggressive males. He may even be able to live with other rats again....who knows!!
Something to think about.

Next, the abscess. I have written several articles on how to care for these things  (I actually have a perverse confession...I LOVE to pop the suckers...is that  sick or is that SICK!? LOL!!)
You can use saline (as you may have read, peroxide can damage the tissues around the wound) or even betadine diluted in equal parts. Pack the hole, if there is one, with neosporin, and if there is no hole, you can still put the neosporin on it.   It may just close up and go away on its own and you wont need a vet...and you can use that money to neuter Hannibal instead!  :-)

Of course if it opens up and doesn't seem to want to heal over and also if you feel better and want to see the vet, don't let my opinion stop you. Its better to be safe than sorry and sometimes these things found on the head and neck area need extra care and even oral antibiotics if they don't clear up on their  own.   It sounds like an abscess though and yes, a bite from another rat can do it just within hours. The bacteria found naturally on the rats skin (just like we have staph normally found on our skin, so do rats) and any bacteria in the rats mouth can cause a pocket of pus to form and eventually swell, and burst...or sometimes it doesn't burst at first and that is when people go to the vet. Some vets lance it surgically and others do what I do and tell you to hold warm compress on it or a heated rice bag that was nuked in the microwave....and let it come to a head on its own and BLOSH! It makes a nasty mess.

Anyhow I hope this helps and thank you for taking the time to research up on your rats with their well being in mind!!

Sandy