Is there any deeper meaning to Lan Wangji stealing the fragrance pouch Mian Mian gave to Wei Wuxian?
Well, yes.
He's jealous of that Mianmian hussy and wants Wei Wuxian to marry him and not her.
Hahahahaha!
Ahem. Let me explain. Flower or fragrant pouches are one among the 12 proposal gifts of ancient China.
Here it is, number 7 among the 12.
The meaning behind the flower satchel is 寄情寄思 (lit. to entrust my love and longing). So a woman giving a man a flower satchel she made in ancient times means, 'Marry me, dude!' And if a man asks for a satchel made by the woman's own hands, it means he's saying, 'You so hot, baby! Marry me!'
The flower/fragrance satchels as a token of great love and promise are most known through two separate legends:
1.Yang Guifei and Emperor Tang Xuanzhong. In which, after Yang Guifei died during wartime, only her flower satchel was reclaimed. The rest of her body was reduced to shattered bones. When he was given this satchel, Emperor Tang Xuanzhong cried and kept it in his sleeves for the rest of his life. This legend was made into a poem 太真香囊子 (The Pouch is steeped in Fragrance) by the poet Zhang Hu.
2. The Book of Jin Jia Wu recorded Jia Chong's youngest daughter Jia Wu falling in love with his lowly aide Han Shou. To discreetly confess her love, Jia Wu made a satchel and gifted it to Han Shou. When Jia Wu detected the familiar scent of his daughter's fragrance recipe on Han Shou's body, he immediately cottoned onto their feelings. Luckily for the pair, Jia Chong was a considerably open-minded man for the time, so he blessed their love despite the gap in social stations and allowed the two to wed.
So Wei Wuxian asking Mianmian for a fragrance sachet is tantamount to asking her to marry him in the eyes of many, and at least very, very flirtatious. That's why Mianmian reacted the way she did.
And this was in front of Lan Wangji.... Imagine how Lan Wangji felt. So it wasn't without reason (other than the fact Lan Wangji was at a very low point in his life then) that Lan Wangji reacted like he did.
So Lan Wangji stealing WWX's fragrance pouch and keeping it on his body for decades after is equivalent to saying, 'You will not marry her. You will marry me!' without actually saying it.
That is to say, Hanguang Jun might not look like it, but he would fit right at home in one of those scandalous, overly dramatic telenovelas where the love rivals duke it out by bitchslapping each other. You just need to speak his language (of actions) to see this.
