Max has always been one to do things by the books.
Back in Valdemar, that led to constant twitting from Heralds and fellow Companions alike about his passion for history and protocol (and related tendency to show up at whatever Collegium classes were near the first-floor windows) - not to mention the not-quite-joking expectation that when he finally went out to Choose, he'd be bringing home the next Chronicler or Dean.
Here in Corona it's... well, it's harder. Not the being here: Max could cite you - if you asked him, which of course no one has - book, page, and line of a half-a-dozen exceptions that mean his presence OutKingdom is, if unusual, not extraordinary. (He'd recited them all to himself as he crossed the Border, then again when he crossed the next, and again every day after that.) It's the simple problem that he's so far from home that no one has heard of Heralds or Companions; and, while they seem to expect intelligent animals, that's all they expect. No one thinks to read a few shelves of histories or etiquette manuals to a horse, no matter how helpful he makes himself.
But he finds a job, such as it is, working for the castle guard (c.f. the last Chronicle of King Sendar, page 200-201, Companion Kantor) as he waits for the nagging feeling inside him to straighten out - first it pulls one way, then another, then nowhere at all. There's a mage out there interfering with his call, he's almost sure of it. But Max hasn't got much Gift in that area to speak of and way out here he's too far to mindspeak for help from someone who does, so he leaves it, trusting that he hasn't been led into something he can't solve on his own. That, after all, is not how it's supposed to work.
So he thinks of his new life as practice: bar access to historical books and his Chosen-to-be, living the culture is the best way he has to get familiar with it and to predict any problems he might have getting both of them back home. And it's not so bad, really, when you come down to it; them thinking him a horse gives him a bit of leeway when it comes to learning what he's supposed to do - and when it comes to overhearing as much as he can to compensate for the lack of real studying.
That's how he learns about the missing princess, though at first he doesn't think much of it beyond a page or three in the footnotes of the report he's constantly mentally compiling about Corona and its laws and customs.
It might have stayed that way, except he's just as indignant as the others in his unit when someone breaks into the castle under his very nose and more determined to catch him than any of them, desperate to be finally doing something useful and earning his disguise's keep. The crown is valuable in itself, which is no doubt why they targeted it, but to the people of Corona (and to the castle guards) it's more, a symbol of that same stolen princess. To Max it's a symbol of propriety and authority - and he can't help but react to their hurt.
As he chases the thief out of the city proper, though, he notices that while he still can't tell where the Call is pulling him, it's definitely getting stronger, more and more so by the hour. What this means, he isn't sure, but he does his best not to think about Cymry... or Kalira.
When he finally - finally - manages to corner Flynn Rider, after a series of misadventures with cliffs and dams and trees that he does not care to think about, he almost wishes he hadn't. It's not because of him; that much, at least, Max is thankful for. But the girl with him, the one who rescued him earlier: she's different, and it's not just her obvious Healing talent.
Something sings inside him, loud and glorious, when he finds himself looking into her eyes. This is her - he's been looking for her his entire life - but at the same time it's not her; the magic is still about her, twisted up and tangled in a strange mess that he can't even begin to understand.
He knows what to do; has always known what to do, deep in the part of him that changed when he came back from the Havens. But now is not the right time to add himself to the trouble that Flynn Rider has landed all of them in, so - he doesn't do it. Not yet. (Kantor waited to choose Alberich: the page of text swims before his eyes like he was staring at the Chronicle itself as he does what the girl tells him, like some kind of trick pony, in half-stunned shock. Rolan waited for Talia.)
After that, of course, there's no question of taking sides against her even if it means helping a criminal.
It's when he's helping them get back to the capital and all the pieces finally start to fall together that Max thinks he might be really, inescapably in over his head, no matter how many times he tells himself that Darenthallis was Prince of Rethwellan and Tashir was the last of the Remeordis. This isn't a dying Kingdom; he should know, he's spent months living in the capital, learning their past and present. She isn't the younger brother in a line already firmly established. The girl - Rapunzel - is Corona's direct heir, and from all he's heard and seen, there will never be more children.
When he finishes this and they go back to the Collegium, he'll be ruining the succession of a country Valdemar has had barely any contact with and causing the worst unprovoked diplomatic incident since he can't even think of when, not to mention taking the person he loves most from a home she's only just found again and a life she never had the chance to live.
He thinks for a long, long time before he accepts that while Companions often choose unexpectedly, they have always chosen. Until now.