This goes back to what I was saying in another thread, but I think that the main problem with Alex and Maria and becoming more established is the fact that they may have become these anonymous blanks that everyone fears toying with for some reason. Dunno for sure though.

That also goes back to something I said on the wiki. Reason they may not have used either Alex or Maria yet is that they could of simply forgotten about them. It's possible they never saw the need to use them back then since they had 11-12 characters to use during the first seasons/episodes. For anyone that has noticed the intro to the show only a few of the characters in that intro have not been used as of yet. Only time will tell if this changes, but from what I've been seeing and looking at the signs it's only a matter of time.