If you want to introduce a new male into your males territory, then I'd suggest getting two new pigs who knew each other well to grow up with, just in case you got one and he didn't get along with your male, you'd have two males all alone.

It's not strictly true what you read as I have had guinea-pigs from different litters get on fine together and have introduced friends guinea-pigs that got on fine together. You just have to know their characters well.

If your pig is prone to getting arsey with you, biting you, then I wouldn't suggest it. If he's ok with you once he's out then I'd give it a go with a young couple of males. Not so young that they've just left mum but young adult pigs. I've got two 9/10 week old male pigs who get on so well with my 1and a half yr old male.

Guinea-pigs will more often than not fight but its not always the case. I just think it depends on each pig and like I said, get two if you're set on getting more, just in case!

Another thing you could do, if they've only just lost their friend, something like a small teddy may help him? Cut along the seams and take all the stuffing out and then add something like wood-shavings or scrunched up paper in case he nibbles it. Possibly rub it around in his bedding (where he sleeps most maybe) so he gets the scent of himself and therefore may find it as a comfort? My gf tried this with her rats after their cage mates had died and they loved their new fuzzy friends

Good luck and give him tons of cuddles!