I moved them across the room from Senga, because I think at least in part the sudden aggression probably has to do with the fact that they can tell there's a girl nearby. Conversely, Nokkun, who doesn't give two figs about Senga, doesn't fight with anybody. But also as they get bigger, I think Sanapig is less and less pleased about Datte chasing him off all the time.
I think their cage is too small for them already, as well, and I'll have to switch them with Senga when I clean them out tomorrow, which Senga is going to be totally pissed off about. to be honest, I'm not psyched either, because I have no idea where to put them for permanent if their cages can't really be next to each other.
*shakes fist* piiiiiiiigs. Hopefully once they get out of their cranky boy stage, everybody'll calm down, but I'm concerned Datte'll have to be separated before that.
ETA: also I'm a little cranky with most of the reputable guinea pig care websites atm, because their solution seems to be 'give them a cage the size of the moon, and also you should drive to Iowa yourself for handpicked hay or you're a terrible owner and person.' I already drove to Kansas for the pigs, thanks, I think I did my bit already.