When we talk about PCs and NPCs in TTRPGs in the sense of not just "character who is played by a player" and "character who is played by a DM" I think we need to acknowledge that's not just an oversimplification of terms, but indeed the wrong way to look at it. "NPC" does not say anything about role they play in the narrative. A villainous NPC has almost as much agency as a PC. A more helpful framing in the context, at least, of D&D and similar adventure-and-combat focused systems, is "adventurer" vs "civilian"; or perhaps, in the context of Campaign 4 specifically, "rock-thrower" and "bystander". This preamble is necessary to talk about why I think Hal is such a fascinating character, but also serves to explore Thaisha, the other Schemer PCs, Thjazi, Aranessa, and a theme that Brennan has brought to Critical Role several times: the metaphorical act of throwing a rock.
Hal, consistently, is depicted as Thjazi's older brother who built a peaceful life in Dol-Makjar and played by the rules. He's sympathetic to the cause of the Falconer's Rebellion but didn't fight it in. He's a family man and a successful artist. He tried the peaceful, legal routes. And they didn't work. So he got a little dirty, but nothing that really stretches his current milieu; he's carrying a sword, but a lot of people carry swords, and he used to carry one anyway so that's not a big change. Hal didn't plant evidence at the Palazzo Davinos. He just had a normal dinner with his long-time colleague and her sister, who wanted to chat him up to get set up with his lead actor, that's all. Sure, he bribed the Marshals to release Misha, but that's just the way of the world, Misha's family and part of the troupe. Hal's just out with his friends Bolaire and Azune and Murray, and it's been a tough few days but nothing that really shatters the illusion of normalcy until he goes down into the sewers in search of a man who is wanted by House Tachonis.
Except, rather like Thaisha in the 4x21 cold open, that's not really true. Thaisha's first druid spell was a dramatic one - Spare the Dying when Alogar fell from a tree. But she'd felt that connection before and had spent 20-odd years pushing it down. Was that when she became a druid? Or just when she admitted it? Hal went with the others to the Palazzo Davinos the night it went dark, and he went to the Lloy estate - that same place in the cold open - to find Thaisha with Occtis's body. The coffin of Olbalad was opened in his house. He knows who Bolaire really is. This isn't the moment he throws the rock. As Brennan narrates, this is just the point when Hal realizes that since Thjazi died, he's been living a different life than the one he might have otherwise. He threw the rock two nights ago; entering the sewers is simply that final step of admitting that his previous life is, indeed, gone. Before, it could be an aberration. Now, it's part of a pattern.
Something notable about Hal is that all of the other Schemers' cold opens during the Seekers arc show the moment when they chose to change something - their rock moment. We see Bolaire's first moments of self-awareness; Murray finagling her way into the Penteveral; and Azune force himself to comply with his parents' wishes and join the Gallows Choir, rather than starve at home. And then we see Hal, who, when Thjazi comes to his door, having ridden two days nonstop in the precursor to what would become the Falconer's Rebellion, chooses not to join him.
In this campaign, we have observed so many of the characters on the day they decided their life had to be different. Some made it a long time ago and never stopped; some made it once, dropped it, and returned; and some are making it now for the first time. But all of them are making that choice - which is very much portrayed as a practice rather than a single shot - and as long as they make it, none of them are being condemned for past missteps. NPCs like Romina or Makmaz, who have only just now begun assist our schemers from the sidelines, when directly asked, are not belittled or chastised for not doing enough or for doing what they do nonviolently; there is even sympathy for characters like Fazir. Hal and Aranessa are not, by the narrative at least, seen as sinners nor failures for picking the rock up some twenty years too late.
I think this is a theme Brennan has been interested in exploring, and I would argue it's one that the Mighty Nein happen to explore particularly well (ie, it's one the CR founding cast, at least, has touched on perhaps without intending it): when do you become an active participant in your story? When do you become an active participant in something larger than that, with the power and responsibility that grants? I think that the embrace of leveling up within the context of the narrative is a means of conveying that mechanically, and perhaps the strongest example of this is in EXU Divergence. We see the PCs of that story become PCs mechanically when they protect the people of Torm's Hill. (I would also argue, actually, that the characters of Downfall become PCs, mechanically, when they are born as mortals). But of course it's not about becoming a PC, since the story grants this status to Romina as well; it's about becoming a person who sees a situation, and instead of saying "well, surely it has to swing back", picks up a rock.