The active perfect identifies the fearing subject; the passive perfect centres the one or thing feared. The first seven positions are as follows.
PronounActive perfectPassive perfect
هُوَخَافَخِيفَ
هُمَا (م)خَافَاخِيفَا
هُمْخَافُواخِيفُوا
هِيَخَافَتْخِيفَتْ
هُمَا (ف)خَافَتَاخِيفَتَا
هُنَّخِفْنَخُفْنَ
أَنْتَخِفْتَخُفْتَ
خَافَ / خِيفَ contrast overtly, but the feminine plural is خِفْنَ in the active and خُفْنَ in the passive. The initial vowel distinguishes voice even where both stems are contracted.