Li Shuwen

An Assassin-class Servant in Nero’s army.
In life, Li Shuwen hailed from the city of Cangzhou in Yanshan County, Hebei. A legendary martial artist, he was celebrated as “God’s Spear” from the end of the Qing Dynasty to the formation of the Republic of China.
In Fate/EXTRA, he fought the main character as the Servant of Julius B. Harwey.
In EXTELLA, he joins Nero’s army after being scouted by her, although it was only by chance that this occurred. Had he been approached by Tamamo first, it is likely he would have joined her army instead.
While his enlistment in Nero’s army was more a matter of chance, he holds honor in the highest regard and has pledged his allegiance to the Crimson Emperor, willing to put his life on the line for the sake of their contract.
If there had been a route where Archimedes tried to kill the main character directly, Li Shuwen would have stepped in to prevent it instead of Nero.
“Why do you protect him [or her]?” Archimedes would ask. “I assumed that Nero is the one to whom you owe your word, not her Master.”
“Well, I never mentioned it to you, but I have a particular bond with this one,” Li Shuwen’s response would begin. “If it is his [or her] destiny to fall in battle, that is one thing, but no one’s going to assassinate him [or her] on my watch. After all, there was once a man who could not accomplish his task because he went along with me for my sake.”
This sense of justice differs from what he displays as Nero’s general, a sense a righteousness born from the experiences he had with the man who was his Master in the past.

Fate/EXTELLA material: Encyclopedia of Fate EXTELLA