The banker is probably the most stand-up guy Moll gets involved with. She really toys with the guy for quite a while, but he's and he's patient enough to wait until she's available so he can snap her right up – when it's proper of course. These upstanding qualities present themselves pretty fast – when the two first meet, Moll knows she can trust him right away, and she's not ever disappointed:
I was fully satisfied that I had a very honest man to deal with; his countenance spoke it, and his character, as I heard afterwards, was everywhere so good, that I had no room for any more doubts upon me. (491)
Despite the fact that the banker is already married at this point, his wife is a "whore" (hey, he said it, not Shmoop), and he wants out. But remember, we're dealing with an honest man, so he wants to divorce his wife before he shacks up with his second – Moll. Little does the poor guy know when he falls in love with Moll that she has, um, a few similarities to his first wife. Perhaps he should have guessed that when she disappears for months on end, but we'd like to think he never really realizes that he ended up almost back in the same boat.
In any case, after Moll returns from Lancashire and gives birth, she rekindles her romance with the banker, once again making note of the fact that he's a stand-up guy:
[…] he was a quiet, sensible, sober man; virtuous, modest, sincere, and in his business diligent and just. His business was in a narrow compass, and his income sufficient to a plentiful way of living in the ordinary way. (732)
We're going to come right out and say it: he sounds kind of dull. He's definitely not as exciting or handsome as Lancashire. But he's safe and honest, and that's enough for Moll's purposes. At the point in Moll's life when she meets the Banker, honesty and safety are exactly what she needs. It's too bad he dies only five years into their marriage; otherwise, Moll might have spent the rest of her life safely set up as a banker's wife – honest, pious, safe, and maybe a little bored.
She really had a good thing going with this guy, but like so many other things in the novel, he is taken from her by forces completely out of her control.