OMG MAARIA LEMME TELL YOU ABOUT HEDGEHOGS I LOVE HEDGEHOGS they are making threatening sounds at each other, they are probably both male and are trying to tell the other "YOU DON'T WANNA MESS WITH ME I BE TOUGH SHIT". Notice how they keep aiming their spiky sides and forehead at each other now and then? It's because if the other attacks, it won't get to bite the sensitive face and other such areas but only meets the protective spikes. Hedgehog-sensei out!