If the question was: Who WAS Skulduggery's brother, then I would understand your confusion as he said he had a brother in book seven, but he died, therefore, past tense.
Haddaba, su'aasha waxay tahay, haddii uu marxuum Cumar Faqi Suldaan ahaa, kana dhaxlay aabihiis Aw Faqi (sida ay sheegeen), maxaa keenay in Faqi Sayid uu la wareego Suldaannimada, maadaama ay ifka ku sugan yihiin dhaxaltooyada Cumar Faqi?