Here is one of several reasons that being famous is kind of weird: People like to surprise you everywhere and anywhere at all times.

Haley Lu Richardson, who has been acting professionally since she was a teenager but found a new and devoted audience playing Portia, the assistant-in-distress on “The White Lotus,” had a big one of these surprises in December.

Ms. Richardson was being interviewed by James Corden, the late-night host and Balthazar undesirable. After learning that his guest was a Jonas Brothers superfan in her youth, Mr. Corden placed a FaceTime call to Nick Jonas. She was profanely delighted.

That experience yielded an invitation from the Jonas Brothers to come to their concert in Las Vegas and to make a cameo in their next music video, both of which occurred in February. Then, one day later, Ms. Richardson flew to Italy to attend fashion week, with her voice still hoarse from screaming for the Jonas Brothers. In Milan, she was greeted with another unexpected encounter.

Seated next to her at the Diesel show on Wednesday was the drag queen Alexis Stone, impersonating Jennifer Coolidge, who played Portia’s boss on “The White Lotus.”

“Oh! Hi!” said Ms. Richardson, 27. Cameras flashed and microphones materialized as people swarmed, forming a U-shape around the pair, on a mission to make content out of this odd couple. But they were also documenting what they may not have realized was a rite of passage for Ms. Richardson: a rising star’s very first fashion show. It was a baptism in the front row — a seat reserved for those climbing the charts of public awareness fastest.

Lately, many of those seats have been going to the Season 2 cast of “The White Lotus.” The fashion world is obsessed; a few of the actors now moonlight as models. The New York Times and other publications have published articles analyzing Ms. Richardson’s kooky costumes on the show. It was only a matter of time before she took her seat, too.

Yet her front-row seat has been the only one, so far, to face down thousands of boxes of condoms: a mountain of lust erected in the center of the Diesel runway.

This was fitting on multiple levels. Ms. Richardson once gave the cast and crew on one of her films customized condoms, she said. (She played a college student who becomes pregnant with twins.)

Also, Diesel is very Portia, a role now so associated with Ms. Richardson that people stop her in the street to yell “Portia!” The brand’s attitude is funny and horny, with a sense of 1990s nostalgia that has given it a Gen Z edge. (Last year, it used sex toys as show invitations and went viral for its micro-micro-miniskirts.) On the show, Portia dressed like a scrambled Y2K mood board and chose adventure with a “Love Island” type of lad over romance with a polite Stanford boy.

But it would be a mistake to conflate the actress with her character, as some people have done.

“When the show was airing and I was going on the internet, searching ‘Portia’ and my name on Twitter — that was overwhelming,” Ms. Richardson said in her hotel room before the show. “It was making me kind of sensitive, because I was like, ‘Hey, just because Portia is annoying and you can’t stand her, I’m pretty great, I promise.’”

Some actors ooze media training, and they seem impenetrable to journalists seeking off-the-cuff authenticity. Ms. Richardson is not that. She told an interviewer two weeks ago, at a New York event, that she was “PMS-ing,” which became the New York Post’s headline. In my interview with her, she asked for permission to use the bathroom and, when complimented on the scent of her hand cream, tried very hard to give it to me.

She also wasn’t flanked in Milan by an agent or publicist or manager or stylist but by her mother, Valerie, whom she’d invited when Diesel offered to pay for a guest. Her mother lives in Phoenix, helping to run her husband’s golf course architecture business. She briefly relocated to Los Angeles when Ms. Richardson was 16 so her daughter could start her career.

Still, even without a publicist, Ms. Richardson knows when to be vague. Asked about rumors that “The White Lotus” cast members hooked up on set — she was on location for five months — she said, “We were there for a long time, and we all got along.” Several cast members lived at a hotel, but Ms. Richardson rented an apartment nearby so that she could bring her cat.

“I think I’m an extroverted introvert,” she said. “I give all this energy when I’m on set. I can be pretty hyper and wild. But then I just want to come home and be around no one.”

She didn’t know what to expect at the Diesel show, she said, other than that she would probably be photographed a lot. She wore a long sleeveless dress in stretchy jersey as soft as velvet. (“Touch it!”)

“I don’t really understand how fashion shows work,” she said. Before the show, her mother bought a Diesel outfit to wear herself, but during Ms. Richardson’s fitting, Glenn Martens, Diesel’s designer, offered to dress her, too, in a loose denim shirtdress.

“I’ve never been great at pictures,” Ms. Richardson said, wondering how she should stand and hold her puffy denim bag and whether it was obvious that her pointy denim shoes were two sizes too big. “It’s hard to take myself seriously enough to pose. The smizing thing, I literally can’t do it. I’ve tried.”

Arriving at the show, she said under her breath: “Don’t have a double chin, don’t have a double chin.” Walking to her seat, she was stopped for TikTok interviews and asked about what sex position she would invent, if she could invent a sex position. She landed on “sexy spoon,” though the interviewer’s phone wasn’t properly recording, so she had to say it twice, graciously, through a cringe.

Then she shuffled to her seat, where she arrived to her Jennifer Coolidge surprise. While filming the series, she had given Ms. Coolidge, the real one, an endearingly vulgar ring and bought one for herself.

Ms. Richardson had been conserving her energy until then, but she let loose a bit during the show. Her “wows” were audible a few rows away, and she grinned at her mother once the soundtrack of orgasmic noises began to play. (Mr. Martens had apologized in advance to Valerie about the soundtrack’s volume, she said.)

Today was their day to be swept up in the fashion machine — fickle and fabulous and occasionally spectacular. A few hours later, they planned to go to the Etro show. But the next day was their day to be a relatively normal mother and daughter on vacation. They had booked a tour group to drive them to Lake Como. There would be a ferry ride and scenic lunch and some shopping.

“Here’s the thing about me,” Ms. Richardson said. “You know how some people are just, like, go-go-go? I’m not that kind of person. Being here and doing two of these shows in one day, I think, is going to be enough for me for a while.”