grammaticality - What rules make “Remember me, who am your friend” grammatical?

An acquaintance recalled this specific example from an English textbook, but it is jarring to my native ear. Is this an example of prescriptive grammarians gone wild?

Answer

It is grammatical, but it is indeed extremely jarring. It is (to me at least) just as jarring (if not more so) to say

*Remember me, who is your friend.

A much better way to express the idea is to say

Remember me, your friend.

On what basis do I say that it is grammatical, if it is so jarring?

1. 
   

   It is usual, in formal English, to make the verb in the clause subordinated by who agree in person with the its antecedent:

   
   

   
   

   I, who am about to die, salute you

   
   

   but not *I, who is about to die, salute you

   
   

   
   


2. 
   

   Though me is the object in the main clause, one of the roles of who is that it can relate an object in the main clause to a subject in a subordinate clause:

   
   

   
   

   I see the man who killed my father.

   
   

   
   

   Here the man is the object of see in the main clause, but who links it to the subject of killed in the subordinate clause.

   
   


3. 
   

   Therefore, logically, the verb after who should be am. But grammar does not always follow logic so smoothly, so it's worth checking actual usage. Searching the British National Corpus for "me , who am" returns only two results, but they are relevant:

   
   

   
   

   I am being taken to the realms of the People, who hate nature as much as they hate me , who am unnatural.

   
   

   [...] you permitted me , who am in any case only a half-time servant, to travel alone.

   
   

   
   

   However, searching for "me , who is" returns no relevant usage - only irrelevant hits such as

   
   

   
   

   Explain to me , who is YOUR GOD?

   
   

   
   

   So logic and usage seem to be in accord - this expression, though ugly, is grammatical.