I used to think Arthur was Vesper One too, but then many things came up that made me believe otherwise. First of all, as SapphireLadybug7 (George) posted on a thread of mine, there is a paragraph in one of the Rapid Fire books where Vesper One sneaks into the mansion in Attleboro (or at least the property, not the house itself). He thinks of Amy as "the girl" and ordered Vesper Six to "take care of the children". If he really was their father he wouldn't think of them in such a dettached (sp?) way. He would want to control them himself, not send Vesper Six to do it.
Another thing: sure, the report in the hidden Vesper room in the bone church. Okay. No one said Arthur had written it. It sounds like the Vespers set the fire. I mean, we know Isabel set the fire, but she's a Vesper (her maiden name was Vesper-Hollingsworth according to the Black Book of Buried Secrets). So quite possibly she was sent by the Vespers to try to get that poem she needed from Hope and Arthur for the Clue Hunt, and then burn the house down regardless of whether she had gotten the poem or not. The other Cahills (Alistair, Eisenhower...) would think Isabel set the fire to kill them because they hadn't given her the poem: hence the two words in the report, coverup succesful. The Vespers would obviously want Arthur dead because he used to be a Vesper, but treasoned them. So it makes sense they'd want to kill him. Hope would've been another target too because she was a Cahill, and Grace's daughter. The reason it only mentioned "mother deceased" and not "father" could be because the Vespers found out Arthur had escaped the burning house. They probably had Vespers watching the area and one of them might have seen Arthur running away from the fire. The reason why he left Amy and Dan behind could be because he realized that the Cahills or Vespers wanted him dead. They would stop at nothing to hurt and kill him, and if Amy and Dan happened to be near him they'd get killed too. Arthur figured if he wasn't anywhere NEAR Amy and Dan, they couldn't get hurt by people trying to kill HIM. And he used the fire as the perfect opportunity to fake his death and leave. If he would've left any other moment, what would the police or Grace tell Amy and Dan? That their father had just run away and left them behind because he didn't care enough about them? So Arthur used the fire to pretend he was dead, and therefore no one would need to wonder where he was; he was supposedly dead.
The Vespers would've known Arthur was alive, as they mentioned in their report, but the Cahills didn't. Maybe Arthur spent the next 7 years running around the globe escaping Vespers and trying not to get killed by them. Eventually, Arthur could have told Grace he was alive. Maybe right from the beginning. This is something else SapphireLadybug7 pointed out: in book 1 The Maze of Bones, Dan was looking at the picture of his parents while he was packing to leave on the clue hunt. He mentioned it was the only picture he had of his parents and he couldn't even see their faces because they were covered by baseball caps. All of the pictures of his parents had been burnt down in the fire that killed them, and Grace always insisted she didn't have any other pictures of them. Why wouldn't Grace have any pictures of her daughter and son-in-law? Didn't Grace keep one single picture of them in her house? Mysterious huh? Well smart, smart SapphireLadybug7 thought that maybe Grace DID have pictures of them, but didn't want to show them to Amy and Dan so they wouldn't be able to recognize Arthur if they ever came across him again. Grace only gave Dan the picture he had because their faces were hidden, and so Dan couldn't see what his father really looked like. They were both too young to remember Arthur clearly anyways.
Do any of you think a father could be cruel enough to his kids, that he would kidnap 7 people they love? That he would use them as guinea pigs and mock them and taunt them by sending them those messages and shooting Nellie? Arthur always seemed like a good man. He wouldn't do that to anyone. Leave alone his kids. Also I think Arthur wouldn't be capable of killing someone personally or any other way. Like the way Vesper One killed that girl at the circus that did the drop-off for him. Arthur wouldn't do that.
Also about the burn mark on his arm. If Vesper One was Arthur and he HAD gotten that mark in the fire that killed Hope, why would he say he got it "at the doorstep of the HATED Cahill family". Why HATED? It was his wife, his kids. Alright, you could argue he didn't really love Hope and he just married her to get info of the Cahills (which I don't believe), but what about his kids? He couldn't hate his kids. If he'd always hated them and really just had kids with Hope to pretend he really was in love and wanted to form a family (which I don't think he did either) then why show so much love to them? Why would he play with them pretending to be "Oscar the dirty fingernail wizard" or "king Bub" wrapped in bubble wrap? Or decorate Amy's room with pink fairy lights for her birthday? He could've just pretended he loved them in front of Hope and then pretended he was too busy to play with them or something. Arthur DID love Amy and Dan, he wouldn't refer to the Cahill family as HATED.
Yet another point. AJT's message to Dan: "Suspend judgement. The whole story is always more complicated than its parts. Wait. -AJT" Umm ok so we infer AJT is Arthur Josiah Trent. What other AJT do we know, really? So my guess is that Arthur sent this message to Dan because he realized Dan and Amy had discovered he used to be a Vesper. He knew they'd be pretty mixed up right now and would be thinking badly of him and doubting him. So he sent Dan the message as a promise he'd explain when the time was right. That way he was both letting them know he was alive, and reassuring them. He figured they'd find out he was alive soon anyways, and staying away from them wasn't going to protect them from anything anymore because they were already in a lot of danger themselves. I think Arthur has been keeping an eye on them for a long time now. He was probably keeping tabs on them in the clue hunt too, making sure thet were alright and ready to jump in to help them if needed. He is doing the same now that they're traveling on Vesper One's orders. IF Arthur was Vesper One, why would he send Dan that message? It would make no sense. Vesper One wants to keep his identity hidden, so why would he send Dan a message which practically yells "HEYY!! IT'S ME, ARTHUR! I'M ALIVE!!". Um, no. Vesper One wouldn't want them knowing he was alive if he was Arthur.
So yeah, there you go. Many of my theories and ideas of why Arthur isn't Vesper One. I think Vesper One might be Damien Vesper. Evidence:
Ok so some people say it can't be Damien because we were told that the last Vesper One died 3 years ago, and Damien would've been Vesper One from the very beginning. Hmm... true, but what about Damien pretended to die 3 years ago, and then came back up or something? He could've pretended he died becase he needed to go undercover for some reason. You know, drop out of the radar for some time.
Another theory: what if he DIDN'T want to be Vesper One? I mean, at first, in the 1500s he would've wanted to. But maybe after some time being Vesper One he realized he needed to back off for some time, go undercover where no one would suspect of him and leave the Vesper One position to someone else. Maybe he needed to get something done that he couldn't trust anyone with. He might have believed he was the only person who could do that job and he didn't trust any other Vesper to do it. Then FINALLY, three years ago, he went and killed the current Vesper One to get back on the position himself because he had done what he needed to do undercover and he knew it was almost time to take his master plan into action.
Yes, it DOES bug me the whole "Damien being 500 years old" thing. But there are many theories to that: Philosopher's stone, elixir of life, maybe even Gideon's ring had immortality powers, who knows? Yes, you say the Philosopher's stone is a myth. But is the 39 clues real? I don't think so (and yes, i've seen the posts here on the MB where people say they ARE real). In a book anything can happen. Anastasia Romanov didn't really live. She died with the rest of her family at the shooting. It was a mystery for many years but it was finally proven she had died some time ago. Well, if the authors can make up Anastasia lived, they can make up the Philosopher's stone is real, right?
So at the very end of the Medusa Plot, I found in the back cover a hidden URL. It was hidden in the background where the Medusa's face was. Hidden were the words:
So I looked it up but a Page Not Found alert came up:
error type 404 (page not found):
This page doesn't exist. Who told you it did? DON’T TRUST THEM!
Hurry: Click here to return to the 39 Clues home page.
I tried again but without a lowercase 'd'and pages 52 and 53 from A King's Ransom came up! It's Vesper One's POV, and only 2 pages long. A lot of the text is covered by black so we can't know what it says. Since the URL was hidden in the Medusa Plot, this was probably a little preview of a King's Ransom before it came out. Why would a chapter about Vesper One have the name Damien in its URL if Vesper One wasn't DAMIEN??
These are just some ideas. All of this is posted on my thread called: Vesper One: Evidence that proves he's Damien. There are comments by other people there too you can go check it out if you're interested.