Who is he?
Nathaniel Cade was a religious man who served aboard a whale hunting vessel in 1867. It was attacked by a vampire who murdered almost everyone on board. Nathaniel Cade was unlucky (or lucky depending on your point of view) enough to be turned into a vampire during said attack. After waking up, and not recognizing himself the young sailor was consumed by a thirst he could not quench. That is until he found the other survivors. He killed, and drained two of his best friends.
After this he was captured by soldiers under direct orders from Andrew Johnson who made a real holy man out of him. Get it, because they peppered him with enough parabellums to--nevermind, just forget I said that.
He grew stronger by the day, and when his wounds healed he begged them to end his miserable existence. They denied him, and instead called upon the voodoo queen. Marie Laveau humored the notion, and asked him if that was what he truly wanted. After realizing that it wasn't, and that there was no way the lord would accept an unholy abomination such as himself he relents.
Marie Laveau refuses to turn Nathaniel Cade into Andrew Johnson's mindless slave, and instead sees that the young sailor could amount to so much more. The voodoo queen uses the bullet that killed Abraham Lincoln to forge a blood oath. This would bind Nathaniel Cade to protect and serve his country, and yet allow him to keep his individuality.
Now for the rest of his unlife he would do the bidding of the presidents of the United States of America, and those appointed by them as liaisons in the contract of the blood oath.
What can he do?
Nathaniel Cade would be classified as a vampire king at this point due to his age but his refusal to drink human blood because of his faith has had a negative impact on his abilities. As well as the fact he wears a cross around his neck. Which, as with any religious paraphernalia, causes vampires agonizing pain. It's noted that said eating habits are considered a fate worse than death to most vampires. If they refuse to drink human blood and drink animal blood instead their bodies degenerate; then they become immobile, decrepit, and riddled with cancerous growths.
Nathaniel Cade has been maintaining these unhealthy eating habits for the past hundred and forty years. So, keep the above in mind when looking at what he is capable of. He has only fed on human blood as of Red, White, and Blood. The latest entry in the series.
Despite this Nathaniel Cade is noted as one of the most dangerous individuals on the planet. This is because he was turned by a vampire king, and therefore was reborn as powerful as him. The local vampires, and vampire kings give him a wide berth. The last time they tried to teach him a "lesson" ended with those same vampires, and vampire kings being made an example of. Tania, another vampire (and Nathaniel Cade's booty call), specifically refuses to hunt any "innocent" humans because of this.
The displayed abilities we see Nathaniel Cade have include superhuman strength, superhuman speed, superhuman durability, and superhuman endurance. As well as superhuman senses (hearing, taste, touch, sight and smell) and a healing factor; he can heal from practically any grievous wound in minutes, and regenerate lost body parts. His motor functions, and intelligence are enhanced; as an extension of this he has a photographic memory. He has a natural connection to the Other Side (an alternate dimension), and can travel freely between it and reality. He can drag his enemies into the Other Side, and trap them there. The Other Side devours a person's body and soul, rapidly ages them, and destroys their mind. Which doesn't faze a vampire, or vampire king due to their physiology.
He does not need to breath, and he does not sweat. His body does not produce an odor. His heart does not beat. Nor does his body produce fatigue poisons, and his stamina is inexhaustible so long as he has recently fed. He only needs to feed after the course of several days but he also feeds in order to heighten his healing factor. As for sleep he does not need it so long as he remains active during the night. If he is active during the day after a week of such activity he must sleep for twelve hours, and in complete darkness. This can be mitigated by drinking blood to restore his stamina.
Diseases, biological weapons, nerve agents, gases, and poisons are useless against him. This includes supernatural afflictions, and advanced mutagenic retro-viruses. Psychic attacks are useless against him, and any attempts to attack his mind would lead to a psychic coming into contact with the Other Side. Which has a habit of devouring their bodies and souls from the inside out.
Then there's the fact that as a natural predator he instills fear in those around him with his presence, and he seems to have some control over it. It is ingrained in human beings on an evolutionary scale, and they naturally fear the dark because of vampires. Often times those who meet him become quivering wrecks during their first encounter, lose control of their bladders and bowels, and black out in some particularly bad cases. However, continued exposure to him allows a tolerance to be built.
He should also have the ability to shape-shift and fly but his eating habits have hindered those particular talents. At least that's what he claims, and it's heavily implied that he is lying in order to conceal the entire extent of his abilities which haven't been reviewed since the 1970s. Now that he has recently started drinking human blood he should have the capability.
What are his weaknesses?
Sunlight does not set him on fire.
However, he is weaker when the sun is out and it's worse in direct sunlight. He operates at 1/4 his usual ability during the day.
He is weak against religious paraphernalia just as any vampire is but he has grown very accustomed to the pain they cause. It's negligible at best, and he has developed a tolerance for it going so far as wearing a cross around his neck. The likes of artifacts of a divine persuasion such as John the Baptist's hand can only make him wince in pain.
His biggest weakness is fire. It deactivates the proteins that make him so durable but even then it's not something that can instantly bring an end to his unlife. He was pinned to a pillar with a flaming sword for nine hours, and lived to tell the tale. This is despite the fact that the sword was burning with a blue-white flame.
As for the limits of his healing factor completely destroying either his heart or his head can end him. That is with emphasis on completely. Just destroying part of them is not enough. Which might not even be a problem as of the moment Nathaniel Cade drinks Megan Roark's blood in Red, White, and Blood.
Which is when his healing factor gets a considerable upgrade. At that point he is able to instantly regenerate from the damage the activating proteins for fibrin caused. Which includes his insides petrifying, and turning into sand; his bones and tissues suffering from millions of fractures, and his brain exploding.
What will this thread cover?
I will be separating his showings into categories, and organizing them that way.
Now without further adieu.