The two have not been seen interacting in the canon timeline. However, they each have a voice lines about each other.
Ganyu mentions how she watched Yanfei grow up and remembers her being a child. She remembers about the words Yanfei would say to her, "you have to keep your promises to live a happy life." Ganyu says how even after that she says how grown up Yanfei is. Also how successful she is due to her studying law, as well that she's beautiful. She understands how Yanfei's work is complicated but seeing how Yanfei handles it without any struggles just makes Ganyu feel steady.
Yanfei mentions how kind and gentle Ganyu is. But is upset at the fact due to her being busy all the time. This is due to Ganyu signing a contract with Rex Lapis after the Archon War. She worries about the work Ganyu has to do as Ganyu doesn't seem to get lots of rest. This is also due to Ganyu liking to work and can commonly be called a workaholic. Yanfei mentions that she understands how she has to work hard and is happy with her job, but it sure less complicated/less work than Ganyu's.
The two share some similarities with each other, as they're both half adepti. With Yanfei's father being an adeptus and her mother being a human. However it's unknown who was the adeptus and human when it comes to Ganyu's parents. As well when it comes from features they have some similarities that they got some of their features from their parents, with Ganyu having horns and Yanfei with antlers. Unlike Ganyu, Yanfei didn't sign a contract with Rex Lapis.
- “Ah, Yanfei... Even back when she was an innocent little girl, she would tell me that "you have to keep your promises to live a happy life." Now, she's grown up to be a beautiful, graceful, and highly successful young woman. Although the work of a legal adviser is complicated, she always seems so carefree. This puts my mind at ease.”
- — Ganyu about Yanfei
- “Ganyu is kind and thoughtful, it's just a shame she's so busy all the time. Most of the time, she's buried in an endless pile of paperwork — the only exception being her nap at noon. Don't get me wrong, I have to put in some hours at work, too. But I'm happy with the job I've chosen, and it's certainly a lot less taxing than hers.”
- — Yanfei about Ganyu
As the two are both half adepti, this causes both of them to be immortal, allowing them to stay together. The two are shipped together because of their opposing elements and personalities. Some also ship them because of their voicelines of each other. A few pieces of fanart of them have been created.
On AO3, there are currently 11 works for this pair.