UGHHHH it would make the Titans the Forgotten Ones! Or something like it! But how would Fen'Harel have avoided the Blight if that were true? Scrap it. Throw that idea straight into the trash. Or maybe the Forgotten Ones were the Titans who remained behind to keep others from gaining access to that which was tainted? Hmmm. I'm not satisfied. Let me think some more.
Hmm. I still think the Forgotten Ones are other former Pantheon members who were wiped from the record (almost entirely, but scraps were left as a "this could be you- don't mess with us" warning by the Elgar'nan faction) when they joined Falon'Din's first failed rebellion and were tossed into the Void with him.
As for the blight and the Void, that's something I'm trying to untangle as well. The Void as a handy pocket dimension Gitmo is probably pretty big. I'm not sure you get insta-blighted just from entering. I think Andruil went looking for trouble, found it, and took in the blight on purpose. She wasn't hunting the Forgotten Ones- she was coming over to their side in the fight against Elgar'nan's Order. (Total Sera move. Screw the big hats, right?) Remember, she comes back howling things "meant to be forgotten" that make the rest of the Pantheon nervous that she's about to turn on them. Those forgotten things are likely the ideals of Falon'Din-Solas and the other Forgotten Ones.
edit: Happy 2000, all!