The Destruction is the name of a path in Star Rail, referring to characters with great survivability and that make sacrifices to increase their damage. Genshin also has such characters: Xiao being a famous example, sacrificing his hp to increase his damage. Itto, Dehya, Kuki, hu tao are other examples of 'destruction' characters that sacrifice a stat to boost something else.
It seems the hydro MC also has an hp sacrifice mechanism via their E. So does this mean more Fontaine characters, maybe even Focalors can do something similar? Then Fontaine could just be Xiao land, the nation of the destruction dao. It could make sense: as hydro resonance boosts hp, if you have excess hp, you got to put it to some use, like perhaps sacrifice some to boost atk or dmg bonus.
Star Rail gives various ideas for what destruction type characters can do: some can sacrifice team hp to boost their own atk. See Blade, Svarog, Jingliu.
C1 is garbage, containing the names of two people who got fired. C2 is better than C1. C4 is also better than C1, also one of the best quests in Genshin. C6 is good.
Heart of Depth 4p, Marechausse 4p, Nymph Dream 4p, Vourukasha 4p can all work.
The real question is what kind of team would HMC be used in? Perhaps their role is that of subdps in say Nilou teams. But even there, Barbara may be more preferable.
There used to be a theory that the mc's abilities are similar to that of the corresponding elemental archon. However Fontaine breaks this trend. Instead the hydro mc's abilities are more similar to Noctis, the hydro dragon.
Thinking about the lore a bit more (and there is a theory in the community on this), gnosis (神之心) literally means 'heart of god', and from 4.2 AQ we know that they are made from the remnants of the third descender. Second, gnosis contain the stolen power of the dragons when the Primordial One (PO) defeated the seven sovereigns. The gnosis were given to the archons, the servants of the PO and Celestia, and so the archons along with Celestia do have that background tension with the dragons. Third, the light realm (as opposed to the human realm and abyssal realm) is the realm of the elements, vishaps, and dragons. So some theorize that visions, gnosis are like 'dragon pearls' of Chinese culture. Or at least, the power over the elements is derived from elemental dragons, similar to dragon authority.
Getting back to the traveler, the mc does not have a vision but is still able to resonate with the elements by touching the statue of the seven. Some suspect that the heartbeat heard when the mc first contacts the anemo statue is that of Nibelung. But anyways, the mc is able to harness the power of the elements, the power of the dragons, without a vision. And so the theory says that is why the hydro mc's abilities are more similar to the hydro dragon. And in general, the abilities of the mc may be more akin to dragons than archons (the servants of Celestia/PO).
For example, the anemo mc summons a tornado (like Dvalin), whereas Venti summons a vacuum hurricane. The geo mc summons rock crystal formations that sprawl out, whereas Morax summons a shield and meteor. The electro mc does have an energy recharge mechanic, but leaves behind amulet things, which is a bit different from how Raiden restores energy with her burst (and has off-field presence too). The dendro mc summons a mushroom and does dendro app via burst, whereas Nahida applies dendro via skill. The mushroom aesthetic is a bit more similar to the realm of the fungi, Nur, and Apep, the dendro sovereign.
We currently do not know the identities of the anemo, geo, electro sovereigns. All we know is that there are dragons such as Dvalin, Azhdaha, and Orobashi.
Also we were teased that Natlan is a nation of dragons, but these dragons have adapted to live with the humans. Would it be similar to the mutated vishap people of Enkanomiya or different?