Do you think it is possible that Sandslash will ever become a vaguely interesting character for you? Will Sandslash probably only become vaguely interesting if he is released for some reason, lost, or mauled apart in a most fun-to-write manner? (or some alternative means of peril)
Who knows? I mean, he doesn't have anything particularly interesting planned, but the characters have surprised me before.
When you say this, do you mean that literally no currently-existing character in the entire fic knows whether or not the Destroyer is aware of being the Destroyer, or just that nobody in terms of the main protagonists, as in Chaletwo, Mark, May, etc, knows that?
It means that Chaletwo, and thus by extension everyone who learned about the War from him, does not know that and as far as he knows nobody else does either (barring the tautological, i.e. that if the Destroyer knows he is the Destroyer, obviously he also knows that he knows he is the Destroyer).
For the purposes of questions about the Destroyer, the mechanics of the War or other important plot-related knowledge, I'm not the all-knowing author; I'm just somebody Chaletwo has explained this all to in detail. The completeness (and accuracy) of the information I can give out will reflect this.