I wrote a piece of poetry for one of my short stories (the main character, Eri, writes poems). It's the following:
Eri, did you feel the earthquake last night?
Are you really sure your apartment's alright?
In which planet where you wandering when it came?
Is reality and the world as you know still the same?
I have my doubts as to whether to put a comma after Eri. Seems to stop the whole flow. Or maybe that kind of punctuation is invisible in poetry?
You need the comma because you are addressing the person. "Did you feel the earthquake last night?" is a complete sentence. Adding "Eri" is a kind of one-word clause. You need the comma to separate the clauses.
My answer may be more of an opinion here but I believe you must keep the comma after Eri.
The use of comma here adds a certain depth to your poem. It makes your reader read it in a particular way. If you were to do away with the comma, your readers will not pause after the name. The effect of the pause (according to me) is that it conveys concern and weight at the same time (depth, like I mentioned). If you remove the comma, the line becomes a little too "plain".
In my opinion, it does not stop the whole flow. Rather it adds a slight "flavour" to the entire flow.
(Not sure if my answer helps a lot)
Another thought on this question: by quoting your own character's poetry, you're also making a comment on her poetry. Is she a "good" poet? Is her style sentimental, form-bound, what kinds of metaphors does she tend to choose (urban life, the natural world, outer space, etc.), does she tend to push the envelope or is she pretty conventional?
If you think she's a poet whose poetry doesn't "flow" well, then you want to make sure her poetry does not flow, even if your own poetry would flow nicely.
In other words, you might want to break some of your own rules about poetry, in order to be true to her poetry and character. You don't necessarily have to write "good" poetry for your character, if she herself is not a "good" poet.
It's not uncommon to do away with punctuation completely in poetry. However, in this case you aren't doing that -- you are using question marks. So yes, you need the comma.
Another way to remove the comma is to put Eri at the end of the line.
