Fabian was ready. Dead quiet and blending it quite nicely in the shadow of the nearest shop, he had already chosen his first hex for them in his head. That was just simple strategy. He was outnumbered - even fucking Carrow could count. So he had to capitalise on the element of surprise.
So as soon as the twins were properly away from the pub, Fabian aimed carefully and sent a conjunctivitis curse right at the face of Amycus Carrow. It was one of the hexes he was very well versed in and if he could incapacitate one, the other would be less of a threat. So his reasoning was, anyway. And as soon as the curse left his wand, he moved slowly along the building, letting the disillusionment charm keep - if nothing else - difficult to see.