Bolaire, Termina, and their relationships to their hosts
One of the many things that struck me watching Bolaire and Termina in episode 30 is that they have very different relationships to their hosts. Bolaire pointed this out in their conversation: "I know you hold closely to your hosts but-" Let's dive in deeper.
A key difference in how Bolaire and Termina relate to their hosts is how closely they identify with them. Termina referred to Amariya in episode 29 as "the lady I am." By contrast, Bolaire said to the Schemers in episode 4, "If I wear a different person I'm still the same mask." Bolaire feels like a completely distinct entity from the person he wears; Termina feels that she is the person she wears.
Termina is drawn toward powerful hosts. "The lady I am is so powerful," she told Bolaire in episode 29, wide-eyed and excited, reveling in the ways they were making each other more powerful. This orientation toward powerful hosts make sense, given that Termina wore Rauwyn herself. Because Termina identifies with her hosts, having a powerful host makes her feel powerful.
Bolaire, by contrast, is drawn toward hosts who are bad people (at least by his standards) who he can judge and punish for their wickedness. There is a lot of evidence at this point to support this view, if we review the hosts we've seen him body snatch:
Aubrus Drime, who failed a morality test that Bolaire set up for him (attacking with deadly intent the moment Bolaire didn't provide the merchandise Aubrus wanted)
A Crow Keeper who Bolaire knew had kidnapped Demodus Blix, beaten him unconscious, and brought him to be sold to a mold monster
Adora, who Bolaire did not choose himself, but he trusted Wick and Tyranny only to put him on a host who deserved it (big asterisk on deserved it, obviously) and indeed, Adora did seem to be an awful person and I doubt Wick would have gone through with it if she hadn't been
Rulius Mercanaud, who Bolaire also did not choose himself, but he trusted Tyranny, who put him on a monster who sucked people's souls out and did hit jobs for the Halovars
I've wondered in the past why Bolaire starved Aubrus, and especially since Bolaire's parting shot at Adora ("You are judged, you horrible woman!"), I am now quite sure that he did it to punish him for his wickedness. It's in the same category as forcing Rulius to watch his brother die: a torment that he feels his host deserved. Bolaire is not oriented toward powerful hosts; mechanically, he cannot benefit from powerful hosts like Termina, because his stats are the same regardless of the host.
Bolaire and Termina's attitudes toward their hosts also lead them to different power dynamics with their hosts. Termina seems to have a more equal relationship with Lady Cormoray. It seems that Termina let her do the talking with her father, Atakani. She listens to Amariya and has internal conversations with her. She says "we're making each other more powerful," indicating a two-way exchange of power. Bolaire, by contrast, utterly dominates his hosts and has no interest in listening to what they have to say unless they have useful intel. (The exception, of course, was when Tyranny briefly wore him; she was not a wicked person for him to punish, so he just quietly took a backseat in her mind.)
What's tragic about this is that Termina's inherent trust in Lady Cormoray, her identification with her, the body-sharing and internal conversation with her, opened the door for a powerful charismatic sorceress to manipulate Termina into trying to kill her only real ally, the only person who truly loved her. Lady Cormoray has taken advantage of Termina's trust and openness to her to turn her into a weapon to turn on anyone deemed an enemy of House Cormoray.
The nightmare scenario that Termina has found herself in, plus what we saw of Bolaire's life before he ran away to become his own mask, paints a tragic portrait of what Bolaire's own life may have been like. Over and over, he was worn and used and put away. Maybe at the beginning, he was more like Termina, talking to his hosts and identifying with them and just wanting to have fun and play dress up with them. But perhaps then his trust was betrayed, and he was manipulated into a weapon. And again. And again, until he became the subservient creature who just served his wearer's will that he was at the very start of episode 13. He was abused over and over, and decided that the only safe alternative was to become the abuser. And he justified it to himself and made it bearable by turning himself into the monster that judges and eats the transgressor as the comeuppance at the end of a dark fairy tale.
The tragedy of Termina and Bolaire is that Termina innocently trusts and shares with her host, following an interpersonal ethic much kinder than Bolaire's with his hosts. But the result of her choice is an ethical disaster: a living nuclear bomb who Lady Cormoray has wrapped around her finger. Bolaire's interpersonal ethic with his hosts is a complete moral mess, but the result of his choices is an anti-authoritarian, anti-Shaper, pro-history, pro-archive, pro-theater, warrior for the truth against all the lies of the Sundered Houses.
Sometimes, relating as ethically as you can with the people closest to you results in a better outcome for society as a whole. The personal aligns with the political. But being kind to the person closest to you can be nightmare for society as a whole if the person closest to you is a greedy tyrant. By the same token, some of the most fiery and effective warriors for the revolution are cruel to the person closest to them. For Termina and Bolaire, the personal and the political are currently not on speaking terms.