Leatherhead
Possibly a Idiot.
There are a significant number of people who managed to make it out of Metrol on the Day of Mourning, mostly by lightning rail. (The other Eberron Domain of Dread, Cyre 1313, deals with the last train of people who couldn't get out in time.) Survivors all have their horror stories about how they ran from the mists watching their family, friends, and neighbors fall behind them.
But if you want to start off being trapped in Dread Metrol, that's easily workable. There is a chunk of an alternate lore dump (The book has a handy Players Edition that leaves in the setting information but leaves out the adventure if you are interested) and an alternate starting scene that could be ran in parallel.
Personally, I think it would be cool two of the PCs were friends or family. One trapped in Metrol and one who managed to escape.
But if you want to start off being trapped in Dread Metrol, that's easily workable. There is a chunk of an alternate lore dump (The book has a handy Players Edition that leaves in the setting information but leaves out the adventure if you are interested) and an alternate starting scene that could be ran in parallel.
Personally, I think it would be cool two of the PCs were friends or family. One trapped in Metrol and one who managed to escape.