He started at the University of Ottawa as a math and physics student. But hooked on "Star Trek," he saw an episode where a disease hype-accelerated some on board the Enterprise and Dr. McCoy had to figure it out.
"After that episode, I was like 'Screw physics. I want to do biochemistry. It's cool,'" Denis said with a laugh.
"I based that decision purely on an episode of TV."
Denis (pronounced Den-ee) went on to get a bachelor's and master's degrees in biochemistry, electing at the start of 2011 to focus on fighting rather than continue with his PhD studies.
On Saturday night, the Montreal-based fighter steps into the Octagon for a second time when he takes on Ronald Delorme in all-Canadian bantamweight battle on a televised UFC card in East Rutherford, N.J.
The man event at the Izod Center features lightweights Jim Miller (21-3) and Nate Diaz (15-7).
Denis' diving into biochemistry illustrates his penchant for setting a goal and accomplishing it.
Denis got into MMA at 20, just looking for something different than lifting weights. He joined a gym and got to meet some fighters. "One thing led to another."
"When I decide I want to do something, whether it's learn about something or accomplish something or whatever it is, I just find a way to do it and I do it," he explained.
He set his sights on the UFC when he learned it was adding his 135-pound weight class.
Winnipeg's Delorme (7-1) is an injury replacement for Johnny Bedford, who pulled out less then three weeks ago. Both men appeared on Season 14 of "The Ultimate Fighter."
Denis (11-2 with 10 knockouts) sees them as fairly similar in body weight: tall with long, lanky limbs.
"Bedford was like a wrestler with good jiu-jitsu that likes to strike. Delorme is more of a judo guy with good jiu-jitsu and sometimes like to strike."
Denis also tried out for TUF, making it to the final stages last summer in Las Vegas where he hung out with Delorme. "He's an nice guy, for sure."
When Denis didn't make the final cast of the reality TV show, he took matters into his own hands. At a Wreck MMA card last October, he finished Nick Mamalis with a devastating suplex slam that knocked his opponent unconscious.
The UFC took notice and the colourful bantamweight didn't disappoint in his January debut, knocking out Joseph Sandoval in Nashville with a string of nasty elbows just 22 seconds into fight.
It's believed to be the fasted knockout by a Canadian in the UFC since Dave Beneteau stopped Asbel Cancio in 21 seconds at UFC 5 in 1995.
The five-foot-seven Denis collected US$45,000 for knockout of the night, which he used some of to take his girlfriend to Cuba for a week and to buy a two-horsepower, top-of-the-line Vitamix blender — the Rolls-Royce of blenders.
It also capped quite a comeback for Denis, who prior to Mamalis had not fought since a March 2010 loss to Yuji Hoshino at Sengoku.
In the aftermath of that fight, he was training for a Wreck MMA title bout when he suffered a pinched nerve in training. He shot in on an opponent "and my body went one way and my head turned like the opposite way — and it just cranked my neck real bad."
His arm went numb but he kept training. The next morning, trying to shower or putting on a shirt were impossible.
"I couldn't barely raise my right arm. I couldn't even lift a peanut butter jar with my right arm." he recalled.
"Not painful, but very weird," he added.
Months of physio followed as he waited for the injured nerve to grow back. When he did finally get healthy, several fights fell apart when opponents pulled out.
Unable to train immediately after the injury, he and a friend drove across Canada and back — camping or sleeping in the car. He met new friends along the way, taught a few seminars and tried his hand at surfing in Tofino, B.C.
"Lots of good memories," he said of the monthlong trip.
A native of Ottawa, he now lives in Montreal where he trains at the Tristar Gym.
He made his pro debut in October 2006 and fought most of his early fights at featherweight (145). He walks around at 155 pounds.
"I love the freedom it gives me," he said of fighting. " I like doing something physical with my body and it's also mentally challenging."
Golf may be the one sport that may have won a split decision over Denis.
As a teenager, he threw himself into the sport and trimmed his handicap of three. But dreams of a pro career were dashed when he was unable to reproduce that in a tournament setting.
He puts it down to youth and inexperience in handling press. Ever the analyst, he notes golf involves "very fine motor skills."
"So if you get nervous, just rotating a wrist or anything a degree off course off your normal swing can mean a horrible shot. So nerves really play a huge part.
"I guess I just learned to respect professional golfers a lot more because they can handle that."
Now he just plays a few times a year for fun.
His fight nickname came from one of his coaches in Ottawa.
"Fight time I'm serious, like a ninja I guess you could say," Denis explained. "But in general I'm not a rough guy, I'm not a mean guy, I'm not going to talk trash. I'm just looking to have a good time — so I guess I'm the ninja of love."