Being an older male, and having been on his own for so long, he may not take to company. All of our males were less than 12 months old when they were put in with others.

About the only thing I can think of is create an area with a wire divide so Greg has one side and another pig has the other side. This way hopefully he will get use to having another pig around. After a while you can try putting them in together. They will still fight but hopefully it wont last long. Otherwise just leave them in their own side. They can see each other so they still have company.

I play with all of my LITTLE PEOPLE every day. It amuses the hell out of my wife watching me lay on the lawn with them.