Barkis is willing informal
If you say that Barkis is willing, you mean that you are willing to do something.
A: "Are you ready for tomorrow's presentation?" B: "Oh! Barkis is willing!"
Boss: "Are you willing to face difficulties?” Jane: “Barkis is willing.”
To be ready for something to happen
The expression "Barkis is willing" first appeared in Charles Dickens' well-known classic "David Copperfield". Barkis is the name of a character in the novel who used this phrase to propose to Clara Peggotty, the maid of David's mother.
It is impossible for a person to change his or her innate or fundamental nature.
He said he would quit alcohol, but he still can't desist from drinking. Once an alcoholic, always an alcoholic.