Both dramas:
- Are BL novel adaptions
- ?re carried out in historical China
- Have action
- One mc is obsessed with the other

Both dramas:
- Are BL novel adaptions
- ?re carried out in historical China
- Have action
- Have evil magic
- The main character is adopted and has no parents

Both:
- BL censhored
- Historical China
- Action
- Strong male leads who have known its other from small age
- Age gap between mc 8yrs in FHLJ & 10yrs in Immortality

Both stories were written by Priest, so as you can guess the relationship between the main characters unfolds the same way. Both pair of partners have a great affection, dependance and trust on each other, but at the same time they make their relationship seem so natural and ordinary without losing their homorous characters.