Responses
Spoilers.
She is not a bitch, she is actually very very nice and loves her sister to the point she fights with blake on who likes her more.
Yes, the manhwa already made it obvious...tho I can say some readers can be very blunt (• ▽ •;)
Diana is a sweet bean that fights with Blake to get Ancia's love and affection.
Also - It's going to get annoying because the FL is always "ooh Diana is then one you love" and bla bla bla but honey Nooo! BLAKE IS IN LOOOOOVE WITH ANCIA!!