As Michael noted, "seduction of" and "seduction by" have different meanings. "Seduction of" is equivalent to active voice and "seduction by" is equivalent to passive voice. In active voice, the grammatical subject performs the action. In passive voice, the grammatical subject receives the action. Active Voice - The dog injured the cat. Passive Voice - The cat was injured by the dog. The cat was injured. Here, a noun substitutes for the verb. ["nominalization" in a grammar book] The cat was injured by the dog. >> The cat's injury by the dog. The story depicts the cat's injury by the dog. She was seduced by ... >> Her seduction by ...

Both sentences say the same thing. To be seduced by someone means you were seduced: sarah was seduced by a friend= Sarah's friend seduced her. It helps to understand the word seduction, because in the second sentence its placement is odd and "her seduction" means the seduction happened to her, it is her experience. And the "by a friend" says who did it to "her".

In both examples, the young girl is seduced by the friend.

"Her seduction by" = she was seduced by someone. "Her seduction of" = she did the seducing, she seduced someone. "Of" shows you the person seduced. and "by" the person doing the seducing.