Many “Grey’s Anatomy” fans were unhappy when Giacomo Gianniotti joined the cast as intern Andrew DeLuca.

And Giannotti hopes to reverse those fans’ feelings when the veteran ABC drama returns Thursday night for its winter premiere.

“I came in directly after they killed off Patrick Dempsey [Dr. Derek Shepherd] so there was this weird stigma that I was replacing him, which is not true at all,” says Gianniotti, recently promoted to series regular. “I’m just a new character on the show. I’m not filling any void,” he adds. “I’ve been getting those crazy tweets: ‘He’s not Derek,’ ‘He’d better stay away from Meredith.’

“But Andrew won’t have any [romantic] intentions with Meredith so fans don’t have to worry about any threat.”

At 26, Gianniotti is the show’s youngest regular, and while he hasn’t been around for long — his character was introduced in May 2015 at the tail end of Season 11 — he’s already had a taste of two big “Grey’s” rites of passage.

“I’ve done some surgeries and I’ve done on-call ‘surgeries’ as well,” he says. The latter refers to DeLuca’s secretive trysts with Dr. Maggie Pierce (Kelly McCreary) — last season’s new kid on the “Grey’s” block — who quickly succumbed to the dashing intern’s gentle ways and fabulous hair.

As for those medical surgeries, they involve a lot more preparation than doffing your shirt.

“My first surgery went terribly because I didn’t know the protocol for so many things, and the other actors were laughing at me,” Gianniotti recalls. “I was just getting everything wrong. Like, once you’re in the OR, your hands have to be by your chest, otherwise you’re no longer sterile — I just didn’t know that, or how to hold my instruments.”

Dr. Pierce is the character who probably knows DeLuca the most, which isn’t saying much. The actor himself is still feeling his way around his character: “If you find out anything, let me know!” he jokes.

So Gianniotti has been filling in the blanks on his own, “I think that [DeLuca] is a very honest, genuine, passionate guy. He’s very driven — I relate to him a lot — and he knows he’s good at what he does. I think he’s more of an introvert and now he finds himself as an adult and maybe he’s rediscovering who he is as a man [and] how to date women.”

Gianniotti’s earlier experience on a doctor series didn’t help him much. The Rome-born, Toronto-raised actor made his first-ever TV appearance in 2010 on “Medicina Generale” — “an ‘ER’ ripoff in Italy,” as Gianniotti puts it. “I played this street punk who lived under a bridge … They had me in a mohawk and piercings. And now I’m on a medical show in America.”