Juǎn Cán Yún is a martial artist initially known for his exceptional skill with a spear, specifically wielding the Téng Léi Qiāng, a weapon that allows him to unleash powerful storm-based attacks. His early motivations are driven by a desire to gain renown as a hero, an ambition fueled by his deep admiration for his sworn older brother, Shòu Yún Xiāo. This admiration leads him to join Shòu Yún Xiāo on the quest to retrieve the hilt of the Tiān Xíng Jiàn.

During this journey, he meets Dān Fěi and quickly develops romantic feelings for her. However, the quest also reveals the morally compromised methods and true personality of his sworn brother, leaving Juǎn Cán Yún deeply disillusioned. This realization causes him to sever their sworn brotherhood, choosing to reject Shòu Yún Xiāo's pursuit of glory to uphold his own principles. His personal philosophy is embodied in his motto: "I will have no regrets disdaining fleeting glory even when my hour comes".

His loyalty ultimately shifts entirely to protecting Dān Fěi, a commitment he solidifies by saving her from an attack by Shòu Yún Xiāo. Following his marriage to Dān Fěi, Juǎn Cán Yún inherits the Dān family's mantle and their sword, the Mù Huī Jiàn. This marks a significant transition in his combat identity, as he goes from a proficient spearman to a novice swordsman dedicated to mastering the Dān Blade Techniques. With the sword, his skill is such that he can summon only one spectral blade, a level below that of other Dān family masters, yet he persists with the weapon even against powerful opponents.

Juǎn Cán Yún's development charts a clear course from seeking personal glory to embracing familial duty and principled resilience. His story becomes anchored by his committed relationship with Dān Fěi, with the two forming a battle couple who fight together against common threats. His path eventually leads to a stable role, teaching Dān family swordsmanship.