Hawštyn Krabat appears to be some kind of Sorb. He was also an anarchist, one of Masque's followers - trapped between the old hard core veterans and the zealous neophytes, and increasingly disillusioned with his leader's means and alliances (particularly with Madam Czarna). As a result, he did not put up that much resistance when Else Rommel and Fernando Jose Salas del Monte ambushed his group in the Wapping Shadow Federation base, and provided the former with a lot of useful information in German. He was later taken in by the Century Club to be interrogated further...
And in 1917, in Stockholm, the man who was Viktor Vaughn would hear the name of Comrade Krabat being toasted by the communists at Karlssen's. Hmm.