Belle Delphine

In the summer of 2019, Kirschner registered a joke Pornhub account and began selling her "GamerGirl Bath Water" product through her online store, garnering her a great amount of media coverage online. Shortly after, her Instagram account was deleted due to community guideline violations. Media outlets have described Kirschner as a cross between an Internet troll and a performance artist, as well as an e-girl. Kirschner has also been cited as an influence on the e-girl aesthetic commonly adopted by TikTok users.

In June 2019, Kirschner posted on Instagram, promising to create a Pornhub account if her post reached 1 million likes. Pornhub responded to the post, calling it "the best news." The post quickly earned over 1.8 million likes; in response, Kirschner held up her promise and created a Pornhub account, to which she uploaded 12 videos. Reactions to this were mixed to negative, as many of Kirschner's fans were disappointed as her uploads were troll videos that featured misleading titles and thumbnails. Each of the videos received poor like-to-dislike ratios, ranging between 66% and 77% dislikes. Pornhub Insights also published a statistics report detailing that Kirschner's videos became the most-disliked in the history of the website. One of the videos, titled "PEWDIEPIE goes all the way INSIDE Belle Delphine", was a minute-long clip which featured "a cat ear-clad [Kirschner] eating a picture of YouTuber PewDiePie, winking throughout." The video drew a response from PewDiePie, who continued with its joking nature. Later in 2019, Kirschner was nominated for a Pornhub Award. In December, Pornhub released their annual statistics report, which included Kirschner as the most-searched celebrity in 2019; "Belle Delphine" was also the fourth-most-searched term in general during the year.

On 1 July 2019, Kirschner launched her online storefront, along with a product that was dubbed "GamerGirl Bath Water". The product was marketed as the remains of her bath water and was priced at $30 (£24). Kirschner stated that the idea to sell her bath water came from continued fan comments on her photos saying they would drink her bathwater. Upon initially selling the product, Kirschner added the note: "This water is not for drinking and should only be used for sentimental purposes." The product was a commercial success for Kirschner, as the first run of the bath water sold out in three days.

In a July 2019 interview with The Guardian, Kirschner stated, "I'm lucky. I can do crazy things and get to see the world react to it, and there's definitely enjoyment in that, even if it's sometimes a little scary. I get a bigger reaction to my weirder content but I think that's only possible because I also make risqué content." She added, "I think it's been amazing and fun, but it's time to move on to new things. I have a diary next to my bed full of crazy ideas. I'm not sure what will top this, but I'm looking forward to seeing what will come next."

On 19 July 2019, Kirschner's Instagram account was banned from the platform. Business Insider reported that Kirschner's account ban came "after a seemingly co-ordinated reporting campaign against her." However, a spokesperson for Instagram told the outlet that her account was not removed due to the aforementioned campaign, but rather because it violated the company's community guidelines. The specific post or reason that led to Kirschner's ban was not provided by the spokesperson, who cited privacy. At the time of her ban, the "belle.delphine" account accumulated over 4.5 million followers, according to Business Insider and Social Blade, a social media analytics firm. Commenting on the ban, she stated she was in contact with Instagram to restore her account.

On 4 October 2019, H3 Podcast co-host Ethan Klein suggested that Kirschner may have had legal trouble due to posting her bath water product. Days later, on 7 October, Kirschner tweeted an image claiming it to be her mugshot, with a caption detailing she was arrested. The image contained a "Metropolitan Police Service" watermark, although there was not any external proof of an arrest, and the Metropolitan Police said the claim could not be verified. Kirschner later followed up the tweet, revealing that someone had stolen her pet hamster at a party and that her vandalization of that person's car resulted in her arrest. Online publications and users raised concerns over the validity of Kirschner's claims due to her previous trolling; some noted that Metropolitan Police mugshots do not contain watermarks. As of May 2020, Kirschner's most recent online activity was uploading her fourth YouTube video on 4 November 2019.

Kirschner's polarizing social media presence has also been noted, with London Evening Standard writing that she "has sparked a flurry of debate online, with fans branding her everything from a master manipulator to a harmful sexist stereotype of gamer girls." Business Insider cited one fan response in particular, which likened Kirschner to a "2019 Andy Warhol". Alex Galbraith, writing for Complex, commented that her "exceptionally weird" stunts "seem to be satirizing the whole idea of sexiness." Citing her as "a surrealist troll that became too much for Instagram", Business Insider ranked Kirschner 89th on the 2019 edition of its UK Tech 100 list. The list's purpose is to feature the one-hundred "most interesting, innovative, and influential people shaping the UK tech scene."

In 2018, Kirschner began to regularly upload pictures of her modeling on Instagram, which had a distinct, self-proclaimed "weird elf kitty girl" aesthetic, and she used accessories such as pink wigs, thigh-high stockings, and cat ears. She also regularly produced cosplay-related content, which included characters such as Harley Quinn and D.Va. In March 2018, Kirschner launched a Patreon account, where supporters could pledge a monthly donation and receive access to self-described "lewd" photosets. At one point, her content garnered over 4,400 supporters on the website. Polygon noted that one follower spent $2,500 in exchange for a personal Skype conversation with Kirschner. In September, she uploaded a second YouTube video featuring her giving a tour of her pastel pink room, while wearing fake braces and thigh-high stockings. Rolling Stone noted that her style in this second video is more in-line with that of the one she later adopted during her rise to prominence on Instagram, which they described as "alien Disney princess porn star."

Once she adopted this new online aesthetic, her Instagram account surged from 850,000 followers in November 2018 to 4.2 million in July 2019. Her content also began to notably and frequently include ahegao facial expressions, which are exaggerated, eyes-rolled-back expressions that signify an orgasm, often featured in adult anime. Complex further described the nature of Kirschner's content, detailing that "along with her more traditional photos, she has posted clips of herself coyly eating a raw egg, shell and all. A scroll through her feed is just as likely to find colorful thirst traps as it is to see photos of her playing with a dead octopus." As she grew in popularity on the platform, Kirschner began to draw controversy for her content. In January 2019, adult content creator Indigo White alleged that while underage, Kirschner used other sex workers' nude photos and represented them as her own. A February video, which showed Kirschner dancing to a song about suicide while holding a gun, also drew controversy. Shortly after it was posted, false rumors of her death began to circulate online.

Her association with both an e-girl image has been covered in the media, with publications having cited her as influencing the e-girl aesthetic commonly found on TikTok. Kotaku and Business Insider have described Kirschner as a "peak self-aware e-girl", and as a figure that some may point to as "a symbol of the first wave of e-girl", respectively. Furthermore, her association with a gamer girl image and its tropes has been particularly highlighted by media outlets. After her GamerGirl Bath Water product went viral on the Internet, Rivera opined, "even the notion of 'gamer girl bath water' plays with all manner of stereotypes about women in games and how some men see them: as mythical unicorns to lust after". Rolling Stones' s EJ Dickson described Kirschner's posts as being more "bizarre" and "ridiculous", rather than "overtly sexual", and opined that: "Such content appears to indicate that Delphine is leaning into — if not overtly parodying — the perception of the ideal girl as a hot, innocent young thing whose desire to play Fortnite is only eclipsed by her desire for nerdy gamer boy dick." Dickson also opined on why Kirschner attracts much controversy, writing that:

Mary-Belle Kirschner (born 23 October 1999), better known by her online alias Belle Delphine, is an English Internet personality, model, and YouTuber. She is most notable for her glamour and cosplay modeling on Instagram. Her posts on the platform featured a risqué and self-proclaimed "weird" aesthetic, and were often influenced by popular Internet memes and trends. As a result of her online activity, she became an Internet meme in her own right.

Kirschner was born on 23 October 1999 in Cape Town, South Africa, and eventually moved to the United Kingdom. Kirschner has had an Instagram account since 2015, and in July 2016, she registered a YouTube account. In August 2016, Kirschner uploaded a makeup tutorial video, demonstrating how to do a cat-eye.