Juǎn Cán Yún is a martial artist first known for his spear techniques, wielding the Téng Léi Qiāng (騰雷槍, Leaping Lightning Lance) to unleash storm-based attacks like Tornado Clearing, Dragon Storm Strike, and Celestial Thundershock. His early drive was gaining renown as a hero, inspired by his deeply admired sworn older brother, Shòu Yún Xiāo. This bond led him to join the quest for the Tiān Xíng Jiàn hilt in Season 1, where he met Dān Fěi and developed romantic feelings for her.

On this journey, Juǎn Cán Yún witnessed Shòu Yún Xiāo's morally compromised methods, leaving him deeply disillusioned. He severed their sworn brotherhood, rejecting Shòu's quest for glory to uphold his own principles, embodied in his motto: "不與浮榮競朝夕，無憾黃沙染身時" ("I will have no regrets disdaining fleeting glory even when my hour comes"). His loyalty shifted entirely to protecting Dān Fěi, demonstrated when he saved her from Shòu Yún Xiāo's attack in the manga.

After marrying Dān Fěi, Juǎn Cán Yún inherited the Dān family mantle and the sword Mù Huī Jiàn (穆輝劍, Solemn Bright Sword). Though proficient with the spear, he became a novice swordsman dedicated to mastering Dān Blade Techniques. His skill allowed him to summon only one spectral sword with techniques like Yang Sunrise, a level below other Dān family masters. This marked a significant shift in his combat identity, yet he persisted with the sword even against formidable opponents.

His path led him to a stable role teaching Dān family swordsmanship at Gosha Academy. Across all media, his relationship with Dān Fěi evolved into a Battle Couple dynamic, fighting together against threats like Xíng Hài. His story charts a course from seeking personal glory to embracing familial duty and principled resilience, anchored by his commitment to Dān Fěi and their shared role in safeguarding mystical weapons.