History’s filled with little ironies. Here’s one: If Scott Brown hadn’t have used the f-word at King Philip Regional High School a few years ago, he probably wouldn’t be going to the United States Senate now.

As you may recall, Brown visited the high school in Wrentham, his home­town, on February 8, 2007, after a his­tory teacher there had heavily criticized Brown’s support for a constitutional amendment that would have allowed vot­ers to ban same-sex marriage.

The night before the visit Brown be­came aware that some students in the class had contributed to an online Face­book

page that praised the teacher and excoriated Brown, taking shots at him and his daughter Ayla.

A couple of the messages used the f-word to praise the teacher. (The vulgar term did not apply to Brown, unlike what is sometimes implied in reports about what happened, although the non-pro­fane

things some of the students posted were ugly enough.) Brown, during his remarks to students, quoted from the messages, repeating the f-word a couple of times and calling out the students who had left the messages by name. A firestorm erupted over the incident, which made regional news outlets and the wire services. Brown initially defended what he did, saying the students needed to own what they wrote. In the face of widespread crit­icism from students and the King Philip School Committee (and amid a smatter­ing of support and sympathy), he later retreated a little from that position, sug­gesting he might have handled the matter differently. “Could I have taken a different tack in presenting the issue? Certainly,” he told me back then, five days after he initially had taken a hard line. “… We’ve done some internal review. You always learn and grow.”

Before that, Brown had let it be known he was interested in challenging John Kerry for his United States Senate seat in November 2008.

After the King Philip incident, though, the news stories mentioning him as a can­didate faded away. It’s not that what he did at King Philip was a war crime. But it showed question­able judgment and it needlessly created controversy — not the sort of publicity de­sirable for a fledgling candidate for higher office who needs to build momentum. Without the KP incident, there’s no reason to think Brown wouldn’t have fol­lowed through with running for the fed­eral Senate that political season. If Brown had run, he almost certainly would have been the Republican nominee in 2008. And he almost certainly would have gotten crushed by Kerry in a year when the top of the Democratic ticket, Barack Obama, carried Massachusetts by 26 points.

And if so, Brown wouldn’t have been the fresh face who seemed to burst on the scene late last month, when voters seemed to start noticing him. As we all know, he started way behind in the polls, but with effective campaigning and television and radio ads he made inroads against an overconfident opponent who didn’t seem to like meeting her constituents. A lot of that early good will for Brown stemmed in part from voters not know­ing who he was, because he had never run statewide before.

Brown’s momentum built in early January, and seemed to explode a couple of weeks ago, resulting in an improbable 5-point victory on election note this past Tuesday. (Aside: I acknowledge my wrong prediction of last week’s column, where I had Coakley winning by 2 points; but I don’t promise not to be wrong again.)

A thousand moving parts went into Brown’s breathtaking victory this week, many of them irreplaceable. But one of them, I contend, was an incident that most people at the time considered a seri­ous self-inflicted wound to his career. The KP incident, incidentally, shows a side of Brown’s character that makes his forthcoming career in Washington almost as intriguing as his campaign: You never know what Scott Brown might say.

He showed it during his victory speech election night when he appeared to offer both of his daughters to young single men in the television audience. (He quickly amended his statement to include just one of his daughters, Ayla, which in a way made it even weirder.) One Norfolk observer this week said, correctly, that Brown’s spontaneity is part of his appeal. He’s a normal guy who of­ten says normal things off the top of his head, including things that don’t sound so good coming from a microphone.

The same what’s-coming-next curios­ity should follow his career in Washing­ton. Brown has a number of positions on issues, but I find it hard to discern a philosophy. He says some conservative-sounding things, but his actual stances dot much of the political spectrum. Dur­ing the campaign he used the old politi­cian’s trick of sounding daring and con­frontational about themes that most people don’t findcontroversial. But it more than just worked. Brown made it work. Karl Rove said election night that Brown seemed to have grown up before his eyes during the campaign, that he had in just a few weeks “grown as a candidate … somebody who’s hit his stride, who’s grown up politically and as a campaigner and as an advocate and as a spokesman, and it has been extraordinary to watch.”

Watching someone grow can be hard: We remember him the way he was. But it’s undeniable: Whether you liked him or didn’t like him before, he’s not quite the same guy now. It’s not just the relatively high officehe is about to enter. Any fool can fall into an officeof any height; American his­tory is littered with such figures. It’s the way Brown went about getting it. It’s as if he began the campaign as a college sophomore and now all of a sudden he’s a world-class professor. You recognize the voice, the accent, and some of the man­nerisms, but the whole package sounds different now. But Brown’s leap up the ladder doesn’t guarantee he’ll climb any higher. The same unpredictability in his utterances suggests an unpredictability in his overall performance. He seems like a grounded man on a personal level, but not so much on a political level. His votes and pro­nouncements in the state Senate amount to a hodgepodge, and there’s no reason to think the guessing game won’t continue. In Martha Coakley, you knew you were getting a reliable liberal vote, someone who would probably mirror John Kerry. In Scott Brown, you don’t know what you’re getting. I’m not sure even he knows what he’s going to do. So sit back somewhere comfortable and get the popcorn ready. This should be interesting.