User blog comment:TheJudicialDoll/White Brick and Black Mourning Dress Speculation/Theory/@comment-6192846-20130725172456/@comment-6192846-20130725190645

Hmmm, it is possible Rin is only the singer and the character in the song isn't portrayed by her (similar to the assumption we make that the orphan in Kept Waiting for A Reponse is only vocally portrayed by Len due to the lack of a proper PV). If so, that widens up the possibilities with your theory.

I agree that the "replica" being an actual mirror is a likely scenario. Unfortunately, the state between all four mirrors is perplexing since we lack all four novels fully translated to connect the dots (as clearly the "mystery" hasn't been fully answered to us in the detail we need it to). Since Allen is noted as just being "touched", I assume this is because the Demon of Vanity can't "multi-task" per say, with fully possessin Riliane.

It leaves Riliane later on and attaches itself to Kyle so this seems to be the likely scenario. So any effect it had on Allen was brief. The hardest part to prove for your theory (and I run into these same problems) is working with available but not fully understood information. Once we have a full translation of Praeludium (maybe Praefatio if necessary), I think your theory can stand on a firmer foundation. I like it so we'll wait and see what becomes of it.