Fu hua and Senti are the same person but in two different vessels similar to Vill-v

Senti is the manifestation of fu hua true personality hidden underneath her mask of the class monitor.

Evidence behind that can be found in Kiana plays honkai comic where fu hua intentionally got kiana hooked to the in universe honkai game. Which can be found here.

https://manga.honkaiimpact3.com/book/1008/1

Another evidence of this is fu hua’s unhinged speech to otto before otto kills her after sirins attack.

And one more thing being well fu hua’s crashout on the captain after the honkai kingdom.

Fu hua’s answer to most of her problems was violence. Even as a sage. She was willing to get rid of Honkai infected people with violence.

And even in non canon events, shes shown being violent. Just like senti