YANQING SIX PHASED ICE THEORY (part 1)
We know that Six Phased Ice is, "It was a unique type of ice known as Six-Phased Ice a substance that adheres to Imaginary Law, meaning that external forces cannot change its form." - Welt in The Voyage Continues (trailblaze quest)
And that March 7th was sealed inside of this Ice for some time "Did Himeko tell you about March 7th? She was trapped in ice, floating through space. We happened upon her and rescued her." And "Whoever sealed her inside the Six-Phased Ice... No matter who it is... did so either to protect or banish her. I believe she had been floating through space for some time." - Welt in The Voyage Continues (Trailblaze quest)
We also know that because of her being sealed in the six phased ice, March 7th doesn't remember anything before she was sealed in the six phased Ice. "How did you get frozen?" - Trailblazer in The Voyage Continues (Trailblaze quest) and "I don't remember a thing. Who I am, where I'm from, my name... it's like everything was erased from my mind. "March 7th" was the day they found me, so it stuck" - March 7th in The Voyage Continues (Trailblaze quest)
We also know that the Ice that March 7th uses to fight is indeed the Six Phased Ice, this is stated by March 7th herself. "I mean c'mon, (Trailblazer), you've got a Stellaron in your body, I have my special Six-Phased Ice powers, and Dan Heng... Uhh, he's got that mysterious past thing going for him..." - March 7th in A Grand Cool Adventure (Trailblaze quest)
Now we'll focus on Yanqing for now.
Yanqing possibly has memory loss, as it is mentioned in game that Yanqing doesn't remember anything about his parents. And this wouldn't be weird because he mentions that "I never my real parents, I was raised by the General since birth" - Yanqing in his 'Yanqing's relationship with General Jing Yuan (character introduction) and "I just thought how I never saw my birth parents. I don't even know if they didn't want me, or if they're already gone..." - Yanqing's message to Trailblazer ((Trailblazer), SOS!)
So it would make sense that he has no memories of his parents because he never meet him. But his earliest memory is of General Jing Yuan teaching him and he also claims that he doesn't have many memories anyway. "But then again, I don't have many memories anyway, so... I'm okay. My earliest memory is the general teaching me" - Yanqing message to Trailblazer ((Trailblazer), SOS!)
And there a possibility that General Jing Yuan is hiding something from Yanqing and that Yanqing might not even be a Xianzhou Native. "I often see other children with their parents and can't help but wonder if the general is hiding something from me..." - Yanqing in his 'Yanqing's relationship with General Jing Yuan (character introduction) and "However, in the family lineage column, Yanqing's lineage was relegated to the category of unknown." - Yanqing's character story: Part II
Back to March 7th.
Since we know that March 7th Ice Powers are Six Phased Ice, let's have a look at cutscenes and her Gameplay which include her Six Phased Ice.
March 7th's Six Phased Ice Is Blue and Pink.
This isn't just shown in her gameplay, It is also shown in cutscene animations. Meaning it wasn't just a random choice. (This statement will connect to something later in the theory).
Back to Yanqing.
None of the other Ice characters shared these Blue and Pink Ice in their gameplay, expect for Yanqing.
Before anyone says "But it might be a coincidence-", I would like to go back to the my eariler statement "This isn't just shown in her gameplay, It is also shown in cutscene animations. Meaning it wasn't just a random choice. (This statement will connect to something later in the theory)", this connects to the fact that Yanqing's gameplay including Blue and Pink Ice isn't a random choice, as he also has Blue and Pink Ice in cutscenes.