Stone archway in Death Chamber

[Sarah]

As you know, I've just finished OotP (again), and as ever when you 
read a book for the zillionth time (probably slight exaggeration 
there), you pick up things that you've missed before, or don't 
understand the relevance of and there are so many unanswered 
questions about the stone archway that I thought some of you learned 
people might have a theory (or two) for.
Right, knowing what we know about a certain person and the archway it 
obviously has a major significance, and we still don't know if that 
certain person really is dead and gone, just gone, or in an alternate 
universe ... but that's not what I'm concerned about because I think 
a lot of those issues will be at least pertially answered in HBP.
What I want to know is "what is the fascination, the mesmerising 
quality of the archway that scares Hermione and entrances Harry?"  
What intrigues him?  What makes him want to walk through it?  Why can 
only Luna and Harry hear the voices and not Neville? (thinking along 
the lines of the Thestrals).  Why does it enthrall Harry, Ginny and 
Neville and yet Ron seems indifferent and Hermione seems absolutely 
terrified?

Maybe I'm a bit slow and these thoughts had never really occured to 
me before, but this time it really jumped out at me as possibly 
significant.
Anyway, I look forward to some interesting theories.
Sarah xx