"I became fascinated with watching people like [famous conductors Herbert] von Karajan and Seiji Ozawa," Nathan recalls. "I often conducted along with these masters on screen, waving and shaping the music with my arms and hands and facial expressions."
Simone, too, drew inspiration from listening to the works of musical masters. She especially admires Italian composer Giacomo Puccini's operas. She says that as a young child she even called her mother "Mamma mia" (my mother), reciting a cry from the famous opera Tosca.
Since then, both young musicians have realised the power of music, and they have been training hard at it.
Last year Simone faced a dilemma: should she dedicate her time to music or refocus instead on school? "I have come to terms with the fact that I am a violinist, body and soul," she says. "So now I am completing high school online. Throughout the year, I learn at the Colburn School of Performing Arts in Los Angeles where a regular day consists of five to six hours of practice."
Nathan agrees that persistence is vital to master an instrument.
"I think the trick to practising isn't monotonous repetition and drilling notes until you collapse. The trick is to combine the power of practice with the fun and love of the instrument," he says.
Yet they do not necessarily endorse the term "prodigy" bestowed on them. "It's a bitter-sweet term," Nathan notes.
"I believe that it is dedication, determination, and support that have got me to the point I am at today," Simone says.
It's not talent, but hard work that matters most, both agree.
Just as a good brush can inspire a painter, so musicians hold a special relationship with their instrument. "I initially wanted to play the double bass, but because I was very small, my mother suggested I play the cello," Nathan says.
Just as music has changed her life, Simone wants to use the power of sound to benefit society.
"I've seen music performances that can help people bond, and generate acts of great kindness. [This can] contribute to a [better] awareness of the extraordinary power of music," she says.
Yet despite their artistry, the two are just normal teens in many ways.
"I love badminton, table tennis, golf, and I am very interested in the relationship between technology and marketing," Nathan says.
Simone adds: "I love hiking, swimming and reading. And I am becoming very interested in film."
They are both enjoying their stay in Hong Kong. "I have read quite a bit about Hong Kong and am fascinated by the interaction between East and West that permeates the city," Simone says.
"I am very excited to enjoy all of the marvellous food as well as the shopping. Most of all, though, I am looking forward to making music with my friends."
Nathan, too, relished his first chance to play music in the city, where his father grew up.
"I'm so excited about being able to share my music [here]. I love Hong Kong culture," he says.
Simone and Nathan will perform at K11 in Tsim Sha Tsui today and tomorrow at 4.30pm and 6pm.
They will also perform at Sha Tin Town Hall (July 29, 7.30pm) and Tsuen Wan Town Hall (July 30, 7.30pm)