Use of modal verbs when writing in past tense

Question

I'm trying to write a story in past tense (I'm using deep POV).

I have two characters who parted ways. One of them is regretting not spending more time with the other before leaving. Since he is thinking about the past, I wrote:

[1] Maybe he could have waited a few more days before leaving.

Later, he realizes that he has the possibility to go back to him. Which of the following should I use?

[2] He could go back.

[3] He could have gone back.

Could is the past simple of can, so I think that sentence [2] would be correct.

On the other hand, could is also used as a modal verb to talk about a possibility in the present, eg. "We could get some ice cream". If I wanted to employ this second use of could, but in the past, I should use sentence [3], right?

If I've not made a mistake up to this point, then I'm confused. Because, if could have is correct in both [1] and [3], then how do I differentiate the two uses? To be clear:

• In sentence [1] I'm referring to the character's past.
• In sentences [2] and [3] I'm referring to the character's present.
• Every sentence must be in past tense since that's how I'm narrating.

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Finally, I would like to express the fact that going back would make leaving (later) more painful. As you can imagine, I'm not sure which of the following I should use:

[4] It would just make leaving more painful.

[5] It would have just made leaving more painful.

Thank you very much in advance!

Answer 1

If you are trying to express regret, I recommend using the modal verb "should". For example, maybe he should have waited a few more days before leaving. You should use "should" because the character believes leaving when s/he did was a mistake.

If you want to express the possibility of something in the past, use could have + p.p because "could" (without have + p.p) is used to talk about abilities in the past (not possibilities). For example: I could have become a professional swimmer. When I was 16 years old, I could swim # meters [...].

The sentences [1] and [3] are referring to the character's past. Only "could" in the sentence [2] can be used to talk about the present or future.

I recommend using the sentence [6] instead of [7] because "Would have + p.p" is used to describe only imaginary or hypothetical situations in the past. So, using it means that the action already took place, and you are reflecting on it in the present.

Answer 2

The difference between "could go back" and "could have gone back" is, as with all perfect tense questions, a matter of completion. If the option of going back is still open at the time of writing then "could go back" is correct. However if the option was open at the time being considered but is no longer open then "could have gone back" is correct.

For example "I thought about Maria, I left her in Manchester last Thursday and went home to Liverpool, if I swallowed my pride I could go back to her" as opposed to "I sat in my Liverpool flat and thought about Annette when I left her in Kabul on the hippy trail in 1970. I could have gone back to her then but it's too late now"