The first thing to realize is that “seducer” does not entail anything lurid. The seducer seeks the affection, not the virginity, of his conquest.
The diary is presented as a “rough copy” of some material he had stolen me another’s desk– although he tries to justify his behavior (“but it is futile for me to try to extenuate my behavior by reminding myself that I did not open the drawer.”).
He wrestles with the “temptation” to go through the materials, which he describes as, “artistically perfected, calculated carelessness.” This “diary” is “neither historically exact, or simply fiction, not indicative but subjunctive.”
There is a great irony in the one who has obtained the diary describes the moment of illicit reading,
When now after having looked into the scheming mind of this depraved personality, I recall my situation; when, with my eye alert for every subtlety, I in thought approached that drawer, it makes the same impression upon me as it must make upon a police officer as he enters the room of a forger, opens his belongs, ….
But the man who is stealing another’s papers and passing them along is himself “depraved” — he admits to falling to temptation, to be drawn and then representing something which is not his.
The irony is heightened because Kierkegaard is pretending that he is someone else presenting someone else’s diary. The final irony is that it is believed that the seducer is a vague autobiography of Kierkegaard himself and a veiled letter to Regine Olson (he wrote this after breaking off his engagement with her as a bizarre defense and explanation).