The 18-year-old Tasmanian has led a life punctuated with links to the Saints, culminating with his first league game against them on Sunday.
A childhood St Kilda supporter, Cornelius held club icons such as Nick Riewoldt and Justin Koschitzke in high esteem. He thought all his Christmases had come at once when one year, Riewoldt attended a camp on the Apple Isle.
"I was a mad supporter at the time, and I went along and had a bit of one-on-one with him," Cornelius enthused, after his debut match in round nine.
"He landed on my toe and broke it, so I ripped his t-shirt."
Riewoldt remembered the incident, and reminded Cornelius of it after they shared the Saints' attacking half for much of Sunday's match.
Koschitzke, who was the youngster's opponent for the first half, also extended conversation after the final siren.
"After the game, he asked me how many games I'd played and I said it was my first one. He told me to keep at it and good luck for the rest of the year," he said.
"It was good to have that at the end of the game. Growing up and supporting them and then playing against them was fantastic."
Cornelius also played with Riewoldt's cousin Jack in their native Tasmania. In even more links to the red, white and black club, his childhood hero was Robert Harvey, he spent a week at Moorabbin during his time with the AIS Academy, and played his first NAB Cup match against Ross Lyon's men.
And on Sunday, he was part of the Lions' second-half revival that nearly handed the Saints their first loss for the season.
"I came off the bench to rotate and slipped on, and was lucky enough to get one over the back that was a bit of a fluke," he said of his first goal, which came at the 12-minute mark of the third term.
"It was an adjustment [going forward], but to get the opportunity to play down back in the seconds and to then have the opportunity to play in the senior level was very good.
"I'm very happy they put their trust in me to have a go there, and hopefully I move on from that."
Cornelius' parents, David and Gaylene, were at Sunday's game, as was his younger sister. He gestured for them to join him in the rooms post-siren, but the family was headed to the airport to catch a Hobart-bound flight.
He said he relished the opportunity to see them on Saturday night, after making a tough move north following last year's draft.
"It was a bit daunting at the start, being away from my family, but the club has been fantastic and I've fit in well ... I'm loving it up there at the moment," he said.
Cornelius said while he had been nervous and "played a game of footy in bed" on Saturday night, his debut had been a day to remember.
"I'm still just coming off a high at the moment," he said.
"It was exhilarating ... It was a good challenge to play on someone like Koschitzke.
"You model your game growing up on people like that, and to play on him and then go forward was fantastic."
