[[WMG: Pawns are [[Franchise/KingdomHearts The Heartless]], only not evil; Arisen are Nobodies, only also not evil.]]
The Pawns are created from hearts consumed by the dragons. They basically imitate life because that's all they remember, but they have no wills of their own. Likewise, Arisen have iron wills that allow them to continue living without their hearts, but no true emotions. Pawns only act and feel human in the presence of Arisen, because they literally complete each other.
* One of the Pawns you meet [[spoiler:down in the Everfall]] essentially confirms this as being true. She says that ever since her Master died, she hasn't even been able to mourn him properly due to losing what little emotion she had while she was with him, so now she just wanders around feeling empty and hollow (though, personally, I think that's a [[TinMan pretty good description of deep grief]]...).
[[WMG: The Brine is actually a sentient hive mind-type being.]]
And it is allied with the Arisen. It can't communicate with humans or pawns, though, so its attempts to save people from drowning are viewed as attacks. Also, it feeds on pawns, which is why they fear it so much.
[[WMG: Alternatively, the Brine is a sort of adventuring tool created by a previous, hydrophobic Arisen.]]
Said Arisen was tired of his enemies washing up on shore, so he created a creature to destroy anything he submerges beyond a certain depth. As a failsafe, he attuned the creature to the Arisen's scar, and also Saurians because he had one as a pet when he was younger.
[[WMG: The Brine is the spirit of the former royal lifeguard.]]
One day he fell asleep at his post, and the duke's 2nd wife drowned. He was executed for his failure, and now his spirit haunts all deep water, rescuing those that fall in, hoping to atone for the one life he failed to save.
[[WMG: Dragon's Dogma takes place in the ''Franchise/DarkSouls'' world...after the age of dark has begun.]]
Gransys is a young nation, cut off from the other states and countries due to the presence of the Dragon; said dragon is very strong, and connected to the rift. In Lordran, the flow of time has become twisted and strange, and beings from other planes or flows of time can appear in another, aiding the occupants of that timeline.
Pawns occupy a similar realm of existence; it's not hard to make the connection that the rift has been corrupted in Lordran due to the high presence of powerful individuals and primal forces.
Not to mention that all over Gransys, you'll find strange swords that have been planted in the ground, indicating that they are burnt out bonfires. This also explains the high population of monsters and creatures, being that with the absence of fire, they have rushed in to take over all but the most civilized areas of the country.
The Seneschal is merely what the White Covenant call their divine being, and holds sway over Gwyn and his fellow lords.
** It's also heavily implied that the Age of Dark is the age of man, and man does seem to be prospering to a degree.
** This actually makes a weird amount of sense if you assume Dragon's Dogma is a sequel to Dark Souls 3. The usurpation ending of Dark Souls 3 flows almost perfectly into Dragon's Dogma backstory: the Ashen One becomes the first Seneschal in response to the plea to "make Londor whole". He uses his raw willpower in combination with the Flame now housed in himself to create a new Age of Man: neither wholly light nor wholly dark. The Seneschal even uses a lot of flame imagery. The Dragon/Arisen is the Seneschal's solution to the waning of the Flame. Perhaps this channeling of the Seneschal's willpower is also what allows humanity access to skills, magic, and leveling without the corrupting power of souls. The Brine could be a manifestation of the Deep (Sea) referenced in Aldrich's story. And, of course, there are the burned-out bonfires and the similar “splintered world” explanation for the asynchronous multiplayer elements. If Aldrich is correct, this new Age of Man will eventually give way to the Age of the Deep Sea (aka Bloodborne, if you subscribe to that theory).
[[WMG: [[spoiler:Stabbing yourself with the Godsbane frees you of your physical body and turns you into an almighty spirit.]]]]
In the final quest, you have the option to [[spoiler:select the Godsbane and stab yourself]]. You first receive the godsbane from the Seneschal, who has it lodged in their chest. Thus, [[spoiler:stabbing yourself with the Godsbane does not kill you. Rather, it removes you from your physical body, allowing you to be an almighty spirit like the Seneschal. This is why you are powerless when you become seneschal, merely being an invisible being]]. It also acts as a test for your pawn. [[spoiler:If they mourn for you, they will get your body. If not, they will remain beside you just like Savan's pawn.]]
[[WMG: [[spoiler:Dragonkin are failed Arisen, and all of them are instruments of the Seneschal.]]]]
[[spoiler:We see that an Arisen who loses to the Seneschal becomes the next Dragon. This is likely Grigori's origin -- he faced Savan at some point after Savan's ascension to Seneschal and lost, and was sent forth from the rift as the Dragon for the first time long in the past. What is not stated in-game is the origin of the lesser dragonkin, such as Drakes, and the Wyverns and Wyrms that appear in the post-game. The Arisen that slew their dragons but died before facing the Seneschal are likely the source of the lesser Dragonkin, following the example of Grigori. The generic Drake, for example, expresses knowledge of the Everfall, stating that 'The seat of god lies beyond'. In addition, the post-game Wyrm in the Watergod's Altar expresses a sense of kinship with the Arisen, referring to him/her as a 'fellow countryman', and expresses knowledge of the Arisen's potential futures as 'man, dragon, or aught else'. While the Wyrm cannot have faced the Seneschal, or he would be a full dragon, this can be explained if you assume all the Dragonkin are under the Seneschal's control. The exception to the rule is Arisen that die fighting the Ur-Dragon, as it claims their hearts for itself.]]
[[spoiler:Which brings up an odd quandary -- where did the Ur-Dragon come from? The answer lies in the Drake in the Conqueror's Sanctuary in the post-game, as it expresses a desire to consume the Arisen's heart, just as the Ur-Dragon does. Thus, the Ur-Dragon is what happens when Dragonkin consume the hearts of Arisen that had already slain their dragons somehow. In each Arisen that has slain their dragon lies the potential to become Dragonkin oneself, and thus consuming such a heart grants greater power to the Dragonkin. The ultimate result of this is the Ur-Dragon. This even explains the ever-increasing generations of the Ur-Dragon, as they are separate Dragonkin that underwent the same process.]]
[[spoiler:Thus, there are several possible fates for Arisen besides the obvious 'simple death'. To accept the dragon's bargain and become like Duke Edmun, to become the Seneschal upon defeating him, to become the Dragon upon failing to defeat the Seneschal, and become a Lesser Dragonkin and potential Ur-Dragon upon dying after slaying their dragon but never facing the Seneschal. There is also the possibility of attempting to fight the dragon and failing, but surviving, which is this troper's personal theory regarding the origin of the Dragonforged. But that's a theory for another entry.]]
[[spoiler:All this explains the ability of Dragonkin to control pawns -- as they are Arisen in a sense, they possess the power to command them just like you do. It also explains why there are so many more Dragonkin after the Everfall opens up, as most Arisen that die after slaying their dragons would end up there, thus why some remain there and why some fly out into the world. What it doesn't explain is how the Wyrm got into the Watergod's Altar despite its size, which, admittedly, continues to elude this troper. Until someone comes up with something he's just going to call it dragon magic.]]
* You didn't mention the Post-Game Wyvern found atop Bluemoon Tower. That one has confused dialogues that state as though it was newly transformed by the time you face it. Also, if I'm not mistaken, your WMG has been proven true as of Dark Arisen. All dragonkin, lesser or otherwise, are transformed Arisen who failed their respective Dragons and/or the Seneschal. And don't forget, it's not just one, two, four generations pass after every Arisen. It's COUNTLESS GENERATIONS after every Arisen that a new one is spawned, meaning it takes THAT long to transform one into a dragon as per the Seneschal's use.
[[WMG: The origins of [[spoiler:The Dragonforged and Sofiah.]]]]
These two are unusual in that their respective backgrounds are extremely ambiguous. [[spoiler:The Dragonforged]] less so, as he is clearly [[spoiler:linked to the current dragon, as he ages and turns to dust upon its defeat. This means he was Arisen at some point after Savan, as Savan killed his dragon and ascended to Seneschal]]. The question is, how is he still here? The obvious conclusion to draw would be that he [[spoiler: took Grigori's bargain and remained immortal that way]], but this doesn't explain his oddities, such as [[spoiler:his burns and his invisibility to most]]. Even beyond that, he even says that [[spoiler:he cast aside all bonds and regrets it]], implying he couldn't have [[spoiler:taken the bargain]]. Instead, the theory is that he [[spoiler:wishes he could have taken the bargain, as then he could have at least partially succeeded. Instead, he faced the dragon in battle and failed, but escaped with his life. This is the explanation for his burns and his knowledge of strategy against the dragon]].
Next is [[spoiler:Sofiah, Selene's Arisen. This one is incredibly hard to pin down, as she is already dead and does not match any of the regular fates of Arisen. The theory for this one is that instead of facing the dragon normally, she devoted her immortality to magical study (possibly due to her already-advanced age making it unlikely that she could face him conventionally) and eventually died in an accident related to said study. Either this accident or her nature as an Arisen are responsible for her appearing as a ghost. Judging from how others describe her, it's likely that her death is relatively recent. If one assumes that she is a post-Savan Arisen, this means her heart, too, was taken by Grigori, possibly close to the same time Edmun's was. Were she alive during the events of the game, she'd probably die like the Dragonforged does after you defeat the dragon.]]
* I worked under the assumption that [[spoiler:Sofiah took the Seneschal's offer of a life of peace. She defeated her dragon (obviously not Grigori), thus regaining her heart and mortality. The Everfall opened up and she made it as far as facing Savan, but when he gave her the option of going home and living quietly, she did. The world was restored to normal; perhaps, however, she felt a little guilty for this, as she went and hid in a forest that no one wants to enter, and she eventually grew old and died. I'd guess she was actually quite ''young'' at the time, as Selene's physical body is of a young girl, not the old woman we eventually see (assuming Pawns "imprint" on their Arisen at the time of their creation, not the time of their death -- you just don't see the effect because you manage to beat the dragon in a relatively short time, so you haven't aged much from creation to death). Not long after the world was restored, Grigori was created from an Arisen that opted to face Savan and failed, starting the whole business with Edmun.]]