Now in his fourth AFL season, Thompson knows what he needs to concentrate on to get the best out of himself.
Where his aggression could once get the better of him - most memorably, when he bumped Western Bulldogs spearhead Barry Hall while he was tying his shoelaces in round nine last year - he has now learned to harness it.
"You've got to be aggressive if you play on these guys but obviously it is a fine line," Thompson, 25, says.
"As a defender you have to be close to your man. One of the things that helps my mindset before and during a game is focusing on being near my man and having that touch and feel, so they can't just get easy possessions."
But while Thompson's game is built on defence, with his focus simply to beat his man, he is increasingly becoming one of North's most attacking defenders.
In 2011, he is averaging more than 19 disposals a game - up from 17 possessions in 2010 - and is ranked sixth at the club in total possessions. In his past two games, against Adelaide and Gold Coast, Thompson has racked up 25 disposals. He is also fourth at the Kangaroos in rebound 50s (39).
Thompson is quick to downplay his ability to win his own ball. He points out he is often led to the ball when playing on elite forwards, while transitions of play can make it easy for defenders to rack up meaningless possessions.
However, the mindset he has recently adopted when contesting the ball is insightful.
Following a slow start to 2011 after an injury-interrupted pre-season, Thompson and North's coaching staff identified he was not attacking the ball enough.
Too often, he was waiting at the back of packs for the ball to spill out, he says.
"You have to be confident with your game," Thompson says.
"I'm just focusing on running through the lines of the footy, just to help the team out."
His new focus has certainly helped North out. The best example came in the Kangaroos' one-point loss to the Sydney Swans in round 10.
Pitted against Sydney Swans co-captain Adam Goodes, Thompson kicked two goals in five minutes in the second quarter.
The first came when he spoiled Goodes in a marking contest just outside North's 50m line. Keeping his feet, Thompson took a handball from Andrew Swallow and burst through an opening between Goodes and Craig Bird, bombing a goal from 50m.
Thompson's second goal was even more impressive. After Daniel Hannebery smothered a Levi Greenwood kick in North's forward 50m, the ball spilled into the centre square. Thompson pounced on it and, with his back to North's goal, stopped in his tracks and pivoted 180 degrees to give Goodes the slip. He then sprinted past Hannebery and converted with a mongrel punt from 60m.
These goals belied the once-widespread perception of Thompson as a niggling negator.
Admittedly, this was a view held outside North, one that gained currency largely on the back on the Hall incident and some of Thompson's previous clashes with Geelong key forward Cameron Mooney.
The aggressive mindset Thompson took into such match-ups was understandable. When the former Geelong VFL defender joined North via the 2007 NAB AFL Draft, the club had a dearth of key defensive options. For several seasons, its defence had been regularly mauled by the likes of Mooney, Hall, Brisbane Lions captain Jonathan Brown and St Kilda counterpart Nick Riewoldt.
Thompson took it upon himself to take the fight up to such forward line 'bullies' and did it so well he finished second in North's 2009 best and fairest.
Fortunately, the Kangaroos' key defensive stocks are now much healthier. With Thompson, Nathan Grima, Luke Delaney and Robbie Tarrant, North now has a mix of options it can send to the competition's best key forwards.
Which has meant Thompson's role has become more varied.
Although North coach Brad Scott still occasionally uses him in key defensive roles on the likes of Goodes, other weeks he will play on smaller forwards. On Saturday night against the Suns, his opponents included Danny Stanley (186cm), David Swallow (186cm) and Nathan Krakouer (182cm).
Thompson says he does not mind who he plays on, confident enough in his own game that he can handle whatever they dish up.
"Before each game you've got to have a set routine and I think I'm getting better at that," he says.
"I always watch vision of my opponent and go over the key notes of how they play, but also the key notes of how I play.
"It just helps to make sure you're doing the right thing."
Still Thompson's always striving to improve. One area where he and North have let themselves down this year has been conceding 50m penalties that have resulted in almost certain opposition goals.
Thompson conceded goals in this fashion to Brisbane's Brown in round nine and to Adelaide's Jack Gunston in round 11.
The latter was labelled a brain fade by Scott in his post-match press conference.
Thompson does not disagree.
"It was just a total mind blank. I wasn't thinking. I just threw the ball back to the umpire and you're not allowed to do that, so it's a 50m penalty," he says.
"I don't think it's a problem. It's just sometimes we lose concentration and you can't afford to do that, especially in the AFL."
Given Thompson's track record of self-improvement, it's not likely to be an ongoing problem.
