Simply put, her fangs were completed because of 'Miss Connie' from the orphanage.
(SPOILERS; for those who haven't reached chapters 100+)
To explain, when Leo was visiting the orphanage she ended up overhearing the adults talking, and basically found out that 'Miss Connie' was actually selling the children from the orphanage. When she gets back to the estate she asks her dad and Leo finds out that not only was 'Miss Connie' selling kids from the orphanage, but that she was actually the ringleader of a human trafficking ring. She finds out everything about 'Miss Connie' was a lie, and that Connie's real name is 'Saura/Sara', and she finds out a whole bunch of stuff about her mother and who her biological father is, and to sum it up.
(Bare minimum explanation here -->) ***You could say that the betrayal of someone she thought was a good person impacted Leo completing her fangs. All the stress and anger leads to her completing her fangs and using them on Miss Connie/Saura, with the intent to kill.
Hope this helps. (●'◡'●)ﾉ
thank you! yes, it does make sense.
Yay, you're so very welcome! I'm so glad it helped a bit ٩(๑❛ᴗ❛๑)۶
uhm hey can u like spoil me who is leo's father?
ok, it's been awhile since i followed up on this but can someone explain to me why or how her fangs are completed again?