(since rose didn’t stick around long enough to correct me)
However much the Breath aspect may end up tying into the idea of “spirit,” I think there is definitely a connection between Breath and confidence. It’s pretty clear in the case of Tavros, the Page of Breath, who had the potential to become a strong person, possibly even a great leader, like his ancestor.
But let’s look at John. He tends not to worry about whether or not things will work out favorably, instinctively believing in himself and his friends.
He seems to, well, breeze through his life, mostly trusting other people to make the plans. He easily takes Terezi and Vriska at their word, because he’s not one to worry overmuch about consequences. This is sometimes to his detriment, but it also fuels the optimism that makes him the heart of his team, and thus the leader. Rose and Dave especially, but Jade, too, can get bogged down in the details: it’s John’s job to see the big picture, and to see it through an optimistic lens.
While the names of classes and their functions don’t always correspond exactly how you’d expect, I think it’s worth noting that an heir, by definition, is someone who receives things without effort, simply by an accident of birth. John didn’t have to work to achieve confidence, like Tavros - it’s his natural state. An Heir shouldn’t be measured by what they have, but how they use it, because they have everything right off the bat.
I think this makes sense for a class which exploits their aspect as a weapon for self-defense. John’s abilities tend to be triggered more or less by accident, or rather, by instinct, because the best defense system is one that can react quickly: the windy thing was first achieved because the alternative was being burned to death; his trusting instincts let Vriska lead him to sleeping on his Quest Bed, without which Jack may have showed up and killed him for real; and in this most recent update, he was able to unlock a new ability when it was the only way to avoid being stabbed (John’s been stabbed before, but this is the first time he’s seen it coming).
Wind powers can be seen as the physical representation of confidence (or vice-versa): confidence can be shown both by a light-hearted, easygoing attitude (the fluidity of air, gentle breezes), and by steadfast certainty (hurricane-level forces which make John among the most formidable players when he exploits his aspect as a weapon).
So, if we can take confidence and wind-related elemental powers to be the defining characteristics of Breath, then an Heir of Breath is someone who comes by those traits quickly and instinctively, and tends to express them in ways that protect his or herself - which of course doesn’t preclude others benefiting from this, because obviously a player who is powerful right out of the gate is a valuable player.
Sounds like our guy to me!
P.S.- A side-note on the passive/active designations of the Knight and Heir. I’ve been mulling this over, and the thing about the Knight and the Heir is that, in my view, they could almost go either way with being passive or active. The Knight is clearly a powerful damage class, not unlike the Prince, though the two classes have very different relationships with their aspects. Though Dave and Karkat tend to direct much of their energy toward keeping others safe, Dave’s personal quest in particular seems to sometimes push him away from others and focus more on self-improvement (imo if Karkat were our only example of a Knight, you would have a lot more people calling it a passive class, a lot of the kid’s issues are inwardly-focused but his actions are almost always about the group’s needs, not his own). Equius never seemed to know whether he was trying to be active or passive, and given that he’s a Derse dreamer that could point in the direction of Heir being passive. And John’s path through the game tended to be one of going where a bunch of meddlesome girls were telling him to go and doing what they told him to do, which seems passive! Part of the confusion comes from the fact that Dave is a Derse dreamer, said to usually be more active personalities, and John is a Prospit dreamer, who are the opposite.
(Now, despite all that, I’m still pretty sure about these designations - John’s powers tend to apply to his own preservation, and while often passive his initial brushing off of Dave while rocketing up to the seventh gate, as well as other moments, show that he can bull-headedly focus on his own desires when he wants to. I still think a lot of Dave’s behavior suggests a passive class, particularly when you consider how much of his active involvement in his session was actually him taking orders from Terezi. Also, Equius’ passive behavior tended to be brought about by the overbearing influence of the Maid and Thief in his session, both active classes as well - plus, he is already very gifted right at the start, like John, breezing through his first two gates without even alchemizing anything).
Something that’s stuck out to me while researching what we know of classes is that there is a scale of how active or passive a class is. It’s brought up twice by Calliope:
…and has also been brought up by Andrew Hussie:
A class can be considered very active or very passive. Doesn’t it therefore stand to reason that there are classes toward the middle of the scale? A class considered to be active, but less so than the other active classes?
My hypothesis is that the Heir/Knight pair are right there in the middle. The Heir is the most passive active class, and the Knight the most active passive class! Thus, while there are still clear limits between what it means to be an Heir and what it means to be a Knight, they tend to be a little more all over the place in terms of who is benefiting or who is giving or receiving the orders, compared to classes further toward the ends of the scale, like Prince or Page. Their dreamer designations also may tell more about their behavior than in other cases, though it should be noted that dreamer designations can say a lot in any case: look at Jade, who is the most active standard class but managed to often play a passive role, though I’d say her instrumental role in getting shit together for the Scratch and the escape to the new session showed that she was active even before she ascended.
(OK so the post-script ended up being about as long as the actual post, sue me)