New TV Season starts tonight! Chuck, Hawaii 5-0, Castle and others!

[Viking Bastard]

I don't either.

I've read interesting speculation that they may be [...]

Spoiler

lost-in-time genetically-improved humans from a distant future

.

My speculation has been along those lines. If they're

Spoiler

time-travelers, The Event may not have happened yet, even though Lee and Sophia spoke of it in the past tense

.