Shen Jiu, a 13 year old slave, watches the last petals fall off the weeping cherry tree in the Qiu manor. Having just survived an especially brutal beating, he makes a wish on that tree. He doesn’t wish for anything big, just to be loved. By someone, anyone, as long as they truly love him as he is. Just one person who cares enough to fight for him.
The next day, a boy who looks almost like Shen Jiu just shows up. He has the same face, but his hair is a dark, reddish brown, like the tree’s bark rather than Shen Jiu's true black hair. His eyes aren’t black either but the fresh green of healthy leaves.
The boy calls him “didi” and himself “Shen Yuan”, and he smiles, and when Shen Jiu gets grabbed, his eyes go cold.
The whole manor is aflame and every single resident dead by the end of that day.
Shen Yuan, who insists on being called “A-Yuan”, “Yuan-ge” or “gege”, drags Shen Jiu to the prestigious Cang Qiong Mountain Sect. He declares the two of them will become cultivators.
They do. They enter the selection ceremony and get picked by Qing Jing Peak.
Qi-ge is there. He remembers Shen Yuan. Everyone at Qiu manor also remembered Shen Yuan, but that’s impossible because Shen Yuan didn’t exist!
But they make it work. Shen Jiu gets to know his new gege and even learns to love him. Gege is protective and likes making things for Shen Jiu. Gege protects him from bullies and helps him learn to read. Gege loves nature, adores beasts but plants even more so, to the point where his notes become its own encyclopaedia.
The thing is, as much as people remember Shen Yuan always existing, they also forget him. They confuse things he did for things Shen Jiu has done. They don’t plan for him on trips, they don’t remember him unless he’s there or getting mentioned by Shen Jiu.
And Shen Jiu is plagued by guilt because gege isn’t real, wasn’t supposed to exist. It’s just that he also can’t let go of him, because gege protects him and he doesn’t hate his mean streak or his pettiness or even all his sharp edges. Sometimes, he even enables Shen Jiu!
But as great and as beloved as gege is, he obviously isn’t supposed to be part of this world. Shen Jiu lives in fear of waking up and finding that Shen Yuan has never existed, the way he didn’t until he suddenly did.
He develops separation anxiety, and he becomes verbally violent towards anyone getting too close to gege. That’s his gege, and nobody who can’t even remember he exists all the time can ever have him!
Meanwhile, Shen Yuan somehow ends up transmigrated. Okay, not good but fine. The system informs him that it’s out of order for now, but that he is Shen Jiu's older twin now.
And judging by the face he wakes up next to, Shen Jiu will later become Shen Qingqiu, which is… bad.
When Shen Jiu - didi? Didi. - asks him who he is, he starts to sweat. Has he been found out? Already?! But when he calls him didi, the little scum villain doesn’t call him out on it. Which is amazing!
Then he sees what their life is like. He knew Shen Qingqiu used to be a slave because of the whole prison arc in PIDW, but he didn’t know it would be like this! Well, he’s had younger siblings before, he has one younger brother now, and in neither world he’ll allow something like this to happen to them!
Besides, he’s the villain’s brother now! He’s supposed to be doing villainous things, probably!
So he takes care of their problem - without leaving any witnesses, he’s learned from the OG villain’s mistakes - and drags them off to Cang Qiong Mountain a bit early.
Things turn out fine! Didi starts calling him gege at some point, he makes friends, he protects his didi and even gets to spoil him a little, and Shen Yuan makes sure nothing happens to make didi turn into a complete villain.
That includes finding healthy outlets for his villainousness, of course! Like bullying and destroying the lives of people who actually deserve it. That’s always fun.
Then they become dual peak lords. The protagonist appears. The system comes online.
And they both think at the same time, for different reasons: “I will not lose my twin to this child”