As a native speaker, I would say "fascination with". You can be "fascinated BY" something, but have a "fascination with". I can't really tell you why, though.

It's not correct. The following sentences are examples of correct English. #1 and #3 have the same meaning as your sentence. #1 uses "fascination with," #3 uses "fascination by." #2 is simple and clear but does not carry the idea of "expressing." #4 means something completely different, but illustrates a correct use of the sequence of words "fascination by." 1) "I want to express my fascination with Lovecraft's tales." 2) "I am fascinated by Lovecraft's tales." 3) "I want to express how much I am fascinated by Lovecraft's tales." 4) "I express my fascination by writing my own horror tales in the same style as Lovecraft's."

I see nothing wrong with "by" here, but, as the other two have said... your best bet is to use "with" in this case!

Hi Chase, The word 'by' is not correctly used here, it would be better to use 'with' (as previously suggested by Rielle) or you could use 'of'. Hope this helps :)

In my opinion, if we use the word "by" in this sentence, it would mean that the the subject wants to show his fascination with the use of Lovecraft's tale. On the other hand, using "to" and "towards" would mean that the fascination is being directed to the object of the sentence which is the Lovecraft's tale.