You know the idea of the frazzled, ill-kempt professor who's a genius at his or her research but totally clueless about the rest of life? That's Thoth, god of knowledge and wisdom and magic, in a nutshell.
When Sadie first sees Thoth, he looks like quite a character: "A lanky man in his twenties stood up, electric guitar in hand. He had an unruly mane of blond hair like Khufu's, and he wore a stained white lab coat over faded jeans and a black T-shirt" (23.98). Even weirder, he has multicolored eyes that look like a kaleidoscope, and his lab coat is covered with hieroglyphs and words in other languages that morph into whatever they represent.
Where does the absentminded part come in? We're getting to that. The kids have to go to Memphis, Tennessee to track Thoth down. He's there in the first place because he was under the impression that it was Memphis, Egypt. Yeah, not quite the same thing. Since arriving, he's been obsessed with barbecue and blues. He has an army of ibises—that's his sacred bird—typing up his various scholarly essays on obscure topics. Starting to sound a little nutty yet?
Thoth tells Sadie and Carter that one of his jobs is to maintain the balance between order and chaos. The implication is that Thoth also helps keep the balance between the gods, since whenever Thoth steps in to take sides—such as helping Isis and Horus defeat Set—things get ugly.
However, Sadie and Carter clearly need Thoth's help to defeat Set, so he agrees to help them on one condition: they have to prove that they're in charge of Isis and Horus, and not the other way around. That way, they stand a chance of not falling back into bad habits like fighting amongst themselves.
The Kanes' interactions with Thoth take on an ominous flavor, though. Bast clues them in when, right before they go in to talk to Thoth, she says to them: "I'll find you when you get out, if you get out…" (23.74) Um, if? Is he really that dangerous? Well, to the gods, yeah: it turns out that Thoth had counseled Iskandar, advising him to ban the gods for the greater good. So it's not guaranteed that Thoth will take Sadie and Carter's side… or whether he'll try to lock Isis and Horus up again.
However, when Thoth agrees to help Sadie and Carter, he follows through. We expect that a mention of the incident will appear as a footnote in his next scholarly essay.