Situation is: a Brazilian woman come to a American young lady.
B: I've come, like you say, Jack Alden.
A: Jack Alden? Oh, you mean John Alden?
B: That's the fellow. I have a message for you. An invitation from a charming young man.
It's from a movie. There's no character called Alden in it. I feel it's some kind of idiom, but Google gives me absolutely no clue what "I've come John Alden" could mean.