The truth is Ed can't apologise because it's not Ed's fault. As vicious as Riddler's vengeance had been, and as much as Oswald may want to twist it into an act of betrayal, he also knows who is to blame, and it's neither Ed nor Riddler.

As the elevator doors drag themselves open, Oswald forces himself away from his impending cloud of melancholy to look out into the street of the Down, the city given over to the Marked members of society. The air is thicker, more humid, and Oswald can already virtually smell the desperation, the dog eat dog of it all.

It takes a moment, then he steps over the threshold.

"Home sweet home, I suppose."