AMID an evolving Geelong defensive line, there has been one constant over the last seven years.

Tom Stewart's midfield minutes have increased, Mark Blicavs plays various roles with aplomb, but it's the softly spoken and especially calm Jack Henry who has been the proven anchor around whom Christ Scott has been able to move the magnets.

"Jack would be, as much as anyone, the mainstay of that group," Scott said following Geelong's 78-point win over Fremantle in round one.

Now 144 games into his career, 16 of which were finals, Henry has been the quiet achiever alongside a host of big personalities.

"He's a bit different to his brother the forward up the other end," Scott laughed.

But after an apprenticeship under the likes of two-time premiership defender Harry Taylor, recently retired Irishman Zach Tuohy, and three-club player Lachie Henderson, Henry understands his new-found responsibility as a leader down back.

"It changes pretty quick," Henry told AFL.com.au.

"For me personally, I started out with Harry Taylor and Lachie Henderson and all these guys, and still with 'Blitz' and a few of those guys who are very experienced players, so it's kind of nice that you can sit in the shadows a little bit and learn (from) them.

"And now to be one of the more experienced guys out there, I think it's important I try and pass down the stuff that I learned from them."

Zach Guthrie's emergence in the last three years, culminating in a second-place finish in the Cats' best and fairest last year, and second-year player Lawson Humphries' confidence have been in no small part due to Henry's composure and consistency alongside them.

His willingness to bring others along with him goes to the heart of what a defender is, working for the greater good of the team, with less focus on individual glory.

"In general, lists are constantly evolving. Our list today compared to two years ago is so different and it's just exciting, so you just keep rolling with it," Henry said.

"I love the camaraderie we have as a defensive group. I love the little game within the game we have, and the little battles and things that we might appreciate more than some of the flashy plays, whether that's a spoil or whatnot.

"Just getting across to help each other, I really enjoy working with them."

Off-seasons training against the Cats' ominous forward line also doesn't hurt.

"I'd say they'd be up there with the hardest forwards to defend, so it's very good for us defenders getting to play on those guys at training. When they're on, they can really be the benchmark," Henry said.

"My whole time here at Geelong, the more competitive our defence and forwards get at each other, the better we get out of each other. When we're getting on top of them some days at training, I think they get themselves going for the next session and really want to get on top of us and beat us.

"It's a really nice, healthy, competitive relationship we have. Glad we don't have to play them on Saturdays."