I'm surprised no one has mentioned this but on the other side of the coin, what the heck are YOU doing snooping on your brother's computer? I mean let's just pretend that the first time was indeed an accident but the second time? don't you think it's a little creepy that you went on your brother's computer to "double-check" what his taste in pornography was? and you are complaining about some perceived violation of your privacy when we know for a fact you violated his privacy and more than once. His computer, his porn.

Or are you going to first tell him how you found out about his fetish before accusing him of taking your things for nefarious purposes? I wouldn't be surprised if he already knew you had gotten into his porn collection more than once, i hope you deleted the recently viewed files or recent places, whatever history happens to be on his OS.