Positioning of comma when assumptions are added to other people's information, as in "I assume" [duplicate]

In a passage of my book, a character tells another that he's "dead". Now, this scene is quite intense, propping up what seems like an imminent fight. The character being threatened has picked up on this, and asks a question in return regarding the information given, with an assumption added. My question is where the comma should come.

Here are the two alternatives (as I see it):

But tell me Gussy, how do you intend to support this claim of my, I assume, imminent death?

Or number two:

But tell me Gussy, how do you intend to support this claim of my, I assume imminent, death?

The first alternative feels much more natural, especially considering how I'd say it. But the second one feels like it makes more sense. I feel it makes more sense because his assumption is the imminence, and not the "death" part. Though, this is quite obvious, considering the "death" part has already been explicitly stated. The imminence on the other hand, is strongly implied. Yet, the first alternative still feels syntactically wrong (if it even relates to syntax). But the first one is also the one that feels the most natural to write. Also, separating the sole adjective of a noun with a comma seems weird.

So, which alternative is correct? If both, which is most common and/or grammatical (if grammaticality is even a factor in such a case)?

EDIT: If I have understood the comments correctly, people are telling me that an alternative could be:

But tell me Gussy, how do you intend to support this claim of my (I assume, imminent) death

That alternative might be a misunderstanding of what the commenters were trying to communicate, but I guess that'll be revealed soon enough.

Solution 1:

Parenthetical phrases

Speech isn't strictly grammatical - especially when people are doing something else, or have something else on their mind. Sometimes you need to add something to what you're saying, but you've already passed the point at which it would be grammatical to do that. That's where parenthetical phrases come in.

In your sentence, the part "I assume" is a parenthetical phrase: it's a temporary diversion from the speaker's train of thought, dropped into the sentence as it occurs to them. A more grammatically correct form of what they're saying would read like:

• "How do you intend to support this claim of what I assume is my imminent death?"

.. however, as you've written it, it's as if the speaker begins to say this:

• "How do you intend to support this claim of my imminent death?"

... but they realise after "my" that they are making an assumption that the death is imminent, and so they insert the additional phrase "I assume" to the sentence to make this clear.

You can use long dashes for parenthetical phrases

Often, parenthetical phrases are separated from their surrounding text using long dashes (the em-dash):

• "How do you intend to support this claim of my—I assume—imminent death?"

(Typographical tradition says you don't put spaces around an em-dash in English, but some publishers do. It's more a question of style than correctness, but you should be consistent).

... or use parentheses ;)

Or, following a the-clue-is-in-the-name rule, you can also use parentheses (round brackets):

• "How do you intend to support this claim of my (I assume) imminent death?"

Placing the parentheses

So, how do you decide which is the better place to put those commas, dashes or brackets? Simply delete the parenthetical part entirely and see if what you're left with is still okay as a sentence.

1. "How do you intend to support this claim of my (I assume) imminent death?"
2. "How do you intend to support this claim of my (I assume imminent) death?"

To me, without having read the rest of your text, version 1 is a more meaningful sentence, but the context of your dialogue might make version 2 better to you.