Looking for a male rat(s)

Hi all,
Since I've had the boys, I've been having ALOT of trouble with Bruiser bullying Ludo. I've tried a re-introduction, and putting Ludo away everytime he goes for him, but I've had no luck so I'm on the lookout for a ratty friend him. Preferably a lone rat, but would be willing to take on a pair. I've been checking gumtree, donedeal etc daily but nothing on it in a while Any age will do I'm in Carlow, but anything near Dublin would be fine because I go up quite alot.