As they go through his fear simulation together, Tris watches Four experience intense terror, and her respect for him grows. When he faces a woman aiming a gun at him, Tris realizes he’s afraid of killing others rather than of being killed himself. The fact that his fear is selfless and ethical makes him seem more admirable and generous in her eyes. Readers also learn that Four’s worst fear involves his abusive father, Marcus, the Abnegation council member who Tris’s father defended near the beginning of the book. Though the revelation comes as a surprise to Tris, it’s less shocking to readers. Both Marcus and Four have dark blue eyes, hinting that they’re related, and on Visiting Day Tris’s mother remarked that Four looked familiar. Additionally, Four told Tris that he never misses his family, suggesting that he left his faction behind to escape it. His father’s violent behavior during the fear simulation explains why. Though Erudite’s attacks on Tris’s father are blatantly false, in Marcus’s case, their accusations are justified.
Up until now, Four and Tris have had trouble expressing their romantic attraction, but the fear simulation brings them closer both physically and emotionally. Abnegation trained Tris not to display public affection, and readers now know that Four is working through an abusive past. But they open up to one another during and after the simulation. Since the fears they experience aren’t Tris’s, she remains objective, and her mental clarity allows her to help Four get through each scenario quickly. Whereas Al was threatened by Tris’s strong performance in the simulations, Four openly encourages it and even finds it sexy. When they’re smashed together in a small box during Four’s claustrophobia scenario, he teases Tris about their bodies touching. The sexual tension of the scene is quickly followed by Tris coming to Four’s defense when the Marcus apparition tries to beat him. They have their first kiss in the chasm shortly after the simulation is over, just after Tris has been at her strongest and Four at his most vulnerable.
The nature of identity, an important theme throughout the book, is especially prominent in this section. Though Four insists that his aptitude test placed him in Abnegation, Tris hopes that he might actually share her Divergence. To her, this similarity is vital: though she is gradually becoming grateful for her Divergence, not just afraid of it, she badly wants to share her experience with someone else. But Four denies he’s Divergent, and he wants Tris to call him by his Abnegation name, Tobias, revealing that he feels closer to that identity than his Dauntless one. Notably, Tris doesn’t return the favor by revealing that her name is actually Beatrice, and readers get the impression that she’s enjoying something of a role reversal. After helping Tobias through his fear landscape, she feels more powerful than ever before.
Even after Tobias and Tris admit their feelings for each other and kiss, their relationship remains complicated. Tobias treats Tris harshly the next day, causing her to question her perception of what happened the night before – something she’s already prone to doing. Tobias even calls her “Stiff” after she panics during the kidnapping simulation. This is a particularly nasty insult, since Peter often uses it, and the simulation has just forced Tris to relive the traumatic night when he tried to kidnap and kill her. Though readers can infer that Tobias is being hard on Tris to avoid suspicion, his behavior is harsh, and Tris’s angry response seems justified.