Trouble w/ the brothers

From the looks of these two, you would think they get along great. But alas, Ein and Stein have either jealousy troubles or they plain don't like each other. I came today to find that Stein had blood stains all over the white part of his fur. He was acting strange, like staying near the garage door instead of following me around the house like the two of them always do. Anyway, I did not find any major cuts, gashes, and the what not, but I'm kinda worried now.
I think we will have to get Stein neutered as soon as we get back from vacation.