There is precedence for Graf's hair being straight blonde, as in post #2784241. The artist seems to flip-flop often on hair color, so this might very well just be Graf. He also draws Graf with varying eye colors between aqua and blue.
Ouch, my mistake. Yes, this is Graf. I was confused at first because the character tags weren't on the source yet and so I winged guesses to the best of my knowledge. Too used to seeing Graf as a plat blonde.