Every week on Billions, one waits for a major eruption. Each time, the dust-ups turn out to be relatively minor road bumps, pitfalls on the way to the final confrontations: face-offs between Bobby (Damian Lewis) and Chuck (Paul Giamatti), Chuck and Wendy (Maggie Siff), and the most elusive of the three primary relationships on the show: Bobby and Wendy.

Last night’s episode threatened to finally break the latter dynamic wide open. And indeed, in Axe’s night-long session with Wendy — not what you typically think of as a therapy appointment but with some similarities — we got closer to understanding each of them, behind their respective masks. But given the nature of the appointment, of course — it was his session — it was mostly Axe. Wendy’s psychology remains more shadowy.

After Axe makes a major lapse in judgment on a trade and loses Axe Capital over a billion dollars, he realizes he needs to consult with Wendy — to figure out what is broken in him mentally, since it’s ruining his business. Unintentionally pitting Lara (Malin Ackerman) against Wendy, Axe admits to his wife that there are some things only Wendy can give him, and tells her he’ll be spending the night in a session with Wendy at the office.

The promise of the conceit is that we will dig further beneath the surface of Bobby Axelrod. We’re led to believe, during the course of Wendy and Axe’s walks, talks, and meals throughout the night in the office, that perhaps it was his fear of what he’d find if he looked under the hood that kept him away for so long. Eventually, Wendy forces him to reveal the truth about Donnie (David Cromer): Axe deprived his friend of months of his life, or even more, by turning down an offer for experimental treatment.

In previous episodes, Axe’s grimaces and abstracted looks pointed indicated that he might possibly be feeling remorse for what he’d done. But in his conversation with Wendy, he opens up, raising one of the questions which inevitably comes up whenever a morally ambiguous character like Axe is dominant on a prestige drama (red alert: The Sopranos, which Billions is only becoming more and more like). On Billions, as usual, it’s posed a bit more directly. “People who have the capacity to feel nothing are called sociopaths, is that what I am?” Bobby asks. Thanks, also, to Axe for defining the term for the audience.

Of course, the fact that he is even worrying about whether he is a sociopath, and thinking about what he did to Donnie in the terms that he did, makes him not quite a sociopath. No, Axe didn’t love Donnie — at least enough. When he died, he felt “relief.” But Axe, at least, “gives a shit,” as Wendy so technically puts it. He is “simply practiced at turning off his emotions.

The question then is: With Axe feeling guilty and unbalanced, will he decide to change his ways — to explore his emotions and motivations before he descends back into battle to save his company? It remains unclear whether the huge loss for Axe Capital will in any way leave him exposed to law enforcement, and if the now-boxed-away case against the company can even be revived at all. But the episode ends with Chuck stealing Wendy’s notes on the session, in his most cold-blooded move in the series yet. So likely, he will find a way to make anything he can use against stick; after all, he’s got burning jealousy on his side.