Complex sentence: When the ritual was performed, Trigon, disguised as a handsome male, emerged and married Arella, who, soon impregnated by Trigon, discovered Trigon's true nature.
Split into simpler sentences: When the ritual was performed, Trigon, disguised as a handsome male, emerged and married Arella. Soon impregnated by Trigon, Arella discovered Trigon's true nature.