First off Dana and Animal Expertise are absolutely and completely wrong on the neutering part. For guinea pigs, neutering does not change their behavior at all, they still fight & attempt to breed sows. There is not any cases where neutering has prevented fighting.
Do not neuter unless you are putting a sow in with them. It's unnecessary, will not help, and any surgery is very dangerous for guinea pigs. Find neutral territory, such as a bathroom floor, and put them both down.
Let them check each other out. If all goes well, continue doing neutral-territory for a few days, then try to put them in a clean & bleached cage (to remove territorial smells that Rambo put there). If there are no sows around, that helps enormously in keeping them from fighting.
The two factors in fighting are territory & sows, and territory problems are eased by introducing on neutral territory & removing Rambo smells from the cage. If it isn't working out, perhaps try getting two cages you can put side-by-side, so while they can't hurt each other they still have a member of their species close to them. They should settle down once they can't reach each other.
I used to have an older guinea pig that was like the gentle giant you described, and I put a young male in with him. They got along very well for months and then out of the blue the older male started fighting with the younger boy, and I had to separate them when I came home and discovered broken teeth on the younger one and a small wound on his foot. (He healed up fine, his teeth grew back.) So it's always very tricky to get them to get along their whole life, but you can try, especially since there are no girls around.
There were sows in the same room as my two males which I think might have corrupted their friendship. It sounds like Rambo's skittishness might help him in being submissive to Gentle Giant, because he doesn't want to get hurt. I can't be sure without seeing him though.
Remember that neutering will not end any sort of fighting problems. Best of luck! :).
Sounds great! Only, you might want to let Rambo decide, such as setting them in a neutral area and see if they get along. Also, you will want them both neutered.
They might have little skirmishes, but that is just to see who is the dominate male. Since there age difference is so wide, The older one will definitely be the dominate.
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.