Sorry to resurrect a dead thread, but tomorrow seems to offer a few real answers to the husband storyline.
First, I do have to repeat: James Spader selling this guy for the time he's on screen is truly amazing. That said, I'm having trouble finding the entertainment value in watching even this bravura performance when the payoff is so often Reddington killing someone, or abetting a criminal.
Which is why the husband storyline is so interesting (so far.) Reddington's statement to his valet or whatever about playing the long game seemed to be in reference to Tom, implying I think that Reddington is taking a chance on Tom either being more than just another criminal or that at least letting Elizabeth play it out will put him in more solid with her. The part about finding out who their enemy is suggests that Elizabeth's connection may be with that person (her real, criminal father? but Reddington knows who that is...)
And a question for people with much sharper eyes: The symbol that Isabella Rossellini's Eberhardt put on Reddington's bodyguard seemed in my memory to be the same symbol etched into the box under the floor at the Keen's house*? Or are my eyes and memory playing me false?
*Strictly speaking, the Keen's ability to keep a house while losing Tom's income and paying their share of his medical bills is a red flag for chicanery. Particularly since elementary school teachers are not especially well paid. (I have my doubts about low level FBI agents too.) But in all probability it's just Hollywood's idea of the ordinary lifestyle.