because the girl sometimes wishes he was her brother.
it probably means she's not serious. Or a non-specific form of address ie mister; kid; neighbour
no they are not related they are very close friends with each other and call each other sister and brother.
Your daughter's husband is your son-in-law. His brother is not related to you. If you need to refer to him other than by name you can say "my daughter's brother-in-law," or "my son-in-law's brother."
If your brother-in-law is the brother of your wife, then his brother-in-law is you.If your brother-in-law is the husband of your sister, then his brother-in-law is you or one of your other brothers.Either kind of brother-in-law can also have brothers-in-law who are married to other sisters he may have. They are not related to you at all.
The brother of your wife's cousin is also her cousin. You can call either of them "my wife's cousin." You are not related to them.
In Scotland, you would call your brother "bruv" or "brother," similar to how you would in other English-speaking countries.
You have no close family relationship with him, in the western European tradition at least. So you call him your brother-in-law's brother. Other cultures may vary.
just call the brother or say stop it
Your sister's husband is your brother-in-law. The English language has no term for the brother of your brother-in-law. You would not be considered to be related to him.
Your brother's son-in-law could also be called your niece's husband, but he is not related to you.
If person married to your brother is a woman? She is your Sister-in-Law.
The English language has no special relationship term for the uncle of your brother-in-law. You are not considered to be related.