It's evident from the surface action in Thief that Leo, Frank's 'boss' (left)
provides Frank (right) and his partner, Jessie, with a baby boy, but as
discussed in my analysis of the movie, a component of the 'hidden' plot
is that Leo has also provided Frank with Jessie herself; or perhaps more
correctly, he has provided Jessie with Frank, so that she and the child
will have a means of support. The audience can't tell from the surface
action that Leo knows Jessie.
From Heat: Neil, Chris's 'boss', confronts Charlene about her cheating
on her husband. Neil demands that she give Chris one more chance to
make a big score and then not blow the money by gambling it away
(Chris lost most of his 'earnings' from the previous robbery due to debts
from a visit to Las Vegas.) This conversation 'points to' the hidden plot
in Thief, in that there must have been behind-the-scenes conversations
between Leo and Jessie.
Neil and his love-interest, Eady. Mann says in the audio commentary to
Heat that as Neil gets more and more involved with Eady, he begins to deviate from his normal routine. What's going on is that he's losing focus,
and is therefore becoming a little less careful concerning his business relationships, and concerning his planning and performance of robberies.
His intuition isn't as sharp as it needs to be.
Near the end of Heat, while Neil's on his way to the airport with Eady, he momentarily senses that something's not quite right after his phone conversation with Nate, his fence. There's a hidden plot whereby Nate is deceiving Neil in some way (possibly by informing on him), but Neil blows
off his own suspicion here, since, as stated above, he's lost focus and is not
quite as careful as he used to be. Mann says in the audio commentary that
when Nate suggests to Neil during the phone conversation that he not stop
by Waingro's hotel room on his way to the airport, it's as if Nate's trying
to convince himself that Neil will not do so. I take this to imply that
Waingro might have information which would expose Nate's deceptive behavior to Neil.
