Re-watching some of the scenes from LBFAD and I can appreciate how tight and consistant the writing really is. Changheng and Dongfang Qingcang are written as perfect foils of each other throughout the series. Initially, they are set up to contrast each other: light vs. dark. Good vs. evil. But as the series goes on, the lines of good and evil blur into each other, you also realize how similar they are. They are both protectors of their people, born with a purpose or destiny, honed from birth to be the perfect to weapon, the perfect soldier, in the fight between the two realms. Both are burdened with immense responsibility, the respect and expectations of their people, to the point that their own personal identity has been erased. Their names are reduced to mere symbols of hope.
And this is why when they meet Lanhua, both Changheng and Dongfang Qingcang fall for her for very similar reasons. Not just for her kindness in sheltering them at their time of need, but Lanhua is also the first person in the Three Realms to see them not as a weapons of war or guardians or protectors of the realm, but as themselves.
Both Changheng and Dongfang Qingcang first meet Lanhua when they are hurt/injured and vulnerable.
On Changheng's first meeting with Lanhua he actually faints and lets his guard down because of his injuries. He wakes up to Lanhua treating his wounds out of purely altruistic reasons, not because of his identity. Not only does she patch him up but she also vows to protect him. It's clear from his reaction that no one has ever protected him before, certainly not his dingbat mushroom gold foil wet noodle of an older brother. The stigma of his mother leaving, the burden of responsibility on his shoulders, is probably the reason why Changheng strives for perfection and why his outward personality is a gentleman devoid of any kinds of desires; the perfect image of an immortal lord protector. With Lanhua, he can just be himself or a version of himself that's allowed to breathe and unwind. Through her, he learns that it is okay to not be perfect at all times and that he is allowed to get tired or to let someone else protect him for a change.
Dongfang Qingcang, similarly, is at his lowest and most vulnerable when she first meets him in the prison matrix. Clueless about his identity initially, to her, he is just "little sinful immortal," one of the many evil doers locked up in the matrix. She knows he is bad/evil and was probably locked up for a good reason. Rightfully, she should turn him in. And yet, despite knowing this, she still feels compassion for his circumstances and sympathizes that he must have been lonely in the tower trapped alone for all those years with no one to talk to. While everyone is concerned about Dongfang Qingcang, the ruthless demon, escaping and causing havoc and cannot wait to villianize him, Lanhua is the only one who misses his company, worries about him, and wants him to accompany her.
Despite knowing he is dangerous and constantly worrying about Changheng coming in and arresting them both for aiding and abetting a wanted criminal, she still chooses to shelter him. Her first instinctive thought when Changheng comes looking is to grab Dongfang Qingcang and jump into the water to save him. When she thinks she is dying because of the poison, she makes sure to tell him to take the spirit stones and leave for safety.
Dongfang Qingcang is obviously skeptical whether she would keep treating him so well once she finds out his real identity. And yet her first reaction to waking up on the boat after his identity reveal is to tell him to leave before they catch up to him. She is visibly frightened and yet she still somehow manages to be cheeky with him! She still treats him well and trusts that he is a good person despite the rumors that suggest otherwise.
Dongfang Qingcang even says something to that effect later on in the Bridge that "people hate me, fear me, and admired me. But she was the only one who loved me, relied on me, helped me through the difficulties. She would follow me even if it meant standing against the world."
Lanhua looking at them without any kind of prejudice and treating them with kindness and compassion that ultimately leads these two to finally see beyond the racial prejudices themselves and accept that good and evil exists on both sides of the war and that despite their differences, these two races might just have more in common than they think.
