What's the Subject in: 'And up here in the corner is me'

It's the same as saying "It is me up here in the corner." - "me" is the subject.

And up here in the corner is me

Answer

'me' is the subject of the sentence. It doesn't comply with standard grammar but it is idiomatic use and that is what it is.

A grammarian would say, And up here in the corner am I.

Reasoning

1.

Up here in the corner is John.

This can be inverted to make:

John is up here in the corner.

2.

Now try the same procedure with 'me'

Up here in the corner is Me.

Me is up here in the corner.

3. The final sentence above is typical of children's speech when they are learning or of adults when they are being 'cute'.

Example: Me want some more sweeties.

The child is clearly using 'me' as the subject of the sentence. It's not correct grammar but that's what it is -- the subject.

I think that with BE we're probably better off subordinating the syntactics to the pragmatics and thinking of the two arguments on either side of the verb as something more like Topic and Comment, which are structurally assigned the syntactic roles Subject and Complement.

In that sort of context there's no problem with seeing a locative as de facto Subject:

A: Do we want to eat at the table or in front of the TV?
B: At the table would be my choice.

And the conventional understanding of the existential construction is that there is the subject:

A: Isn't there anybody might help?
B: Well, there's Jack.^†

Alternatively, you may think of the locative as an attributive which has 'fused' with its head: this up here on the corner. The important thing is that up here in the corner is Old Information, and me is New Information.

On either analysis the understanding of pronominal case becomes clearer. In the vernacular—and to a growing extent even in the most formal registers—what we traditionally call the 'nominative' is not the form which marks the Subject but the form which marks a (unique, non-conjoint) Topic. All other uses call for the base form, hitherto called the 'accusative'.

In your example the locative is the Topic, assigned the syntactic role of Subject, and the pronoun is the Comment, assigned the syntactic role of Predicate Complement.

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^† Yeah, I know, the conventional understanding is that there is a pronoun, bleached of locativity. I think that's an unnecessary inference from the Subject role and suggest it's more parsimonious to think of it as the ordinary locative, bleached of deixis.

Verb agreement would point to "me" being the subject:

“And up here in the corner is me” vs “And up there in the corner are us".

Accusative "me and "us" are the 'normal' forms here, the absurdly formal nominative "I" and "we" also being possible.

But only the nominative "I" would be possible in the non-inverted equivalent:

"I am up here in the corner".

The PP "up here in the corner" would then be a locative predicative complement.

A different approach. Let's delete words that clearly aren't the subject and don't chance the form of the sentence:

And up here in the corner is me

'And' clearly isn't the subject, and 'in the corner', as 'the corner', being preceded by 'in' clearly isn't the subject, doesn't contain the subject. That leaves us with:

Up here is me

Now, I think this may in fact the same construction as 'Here is me' or 'Here I am'. If it's different, then 'up here' makes 'here' a straight noun, but not the subject.

That leaves us with 'here' and 'me'.

Re 'here', see What part of speech does “here” have in “I am here”? - TLDR, 'here' is either:

• an adverb, or
• a proximal deictic locative predicate

So that leaves us with 'is' (nope), or 'me'. I'd settle on 'me' as the subject. Perhaps it should be 'And up here in the corner am I'

If you want examples of similar construction of this peculiar inversion of word ordering:

• 'Here stand I'
• 'That say you!'
• 'And up here in the corner is an apple'

Removing the inversion, it's simply 'And I am up here in the corner'

We might need to consider the possibility of an elided subject. 

Let's start with a simple and unsurprising utterance: 

That's me. 

This sentence works in any English dialect that allows the complement to take an objective form.  It even stands as an argument for using the label oblique in preference to objective.  The "me" is not an object, but it is part of the predicate.  The subject, of course, is the demonstrative pronoun "that". 

Person and number are irrelevant in the complement.  "That's me", "that's you", "that's him", "that's us", and "that's them" are also simple and unsurprising.  They all work with the subject "that" and the verb "is". 

Adding prepositional modifiers is easy: 

That up here in the corner is me. 
Up here in the corner, that's me. 

At this point, the demonstrative property of the pronoun is redundant.  We have modifiers that carry a locative semantic.  Other than marking that there is a subject, "that" doesn't have a job to do.  This could be sufficient explanation for an elision: 

[That] up here in the corner is me. 

In turn, elision explains an otherwise bizarre flexibility in the verb's grammatical number: 

[That] up here in the corner is us. 
[Those] up here in the corner are us. 

The verb "to be" retains its normal use and behavior as the copula.  The complement "me" simply specifies what [that] is.  Different dialects can have different preferences regarding the choice between [that] and [those] without needing a further grammatical explanation.  The implication that such prepositional phrases need something to modify is satisfied by the existence of an understood, unwritten subject. 

An elided subject isn't the only possible explanation.  However, as explanations go, this one is simple, clear, and productive.