Elias' or Elias's? I am struggling with the correct spelling of it and would appreciate some help on the matter, thank you! :)
The general rule is that the possessive of a singular noun is formed by adding an apostrophe and s, whether the singular noun ends in s or not. The possessive of a plural noun is formed by adding only an apostrophe when the noun ends in s, and by adding both an apostrophe and s when it ends in a letter other than s.
Apostrophe -- The Punctuation Guide
Actually, both ways are correct. If a proper name ends with an s, you can add just the apostrophe or an apostrophe and an s. See the examples below for an illustration of this type of possessive noun.
Have you seen James’ car? Correct
Have you seen James’s car? Correct
But when you have a plural noun that ends in s, add just the apostrophe. This is also true when you have a proper noun that’s plural.
This is the boys’ bedroom.
My parents’ house is a lovely old one.
I have naught to add to this subject (personally have always used a simple s => apos only rule without remarks).
Notwithstanding, would like to point out that if your goal is creative writing, rather than a literary essay for an english teacher's review, nuances of grammar might not prove the most beneficial use of your time. If it's so bad as to catch the casual reader's eye (breaking immersion), then work on that; otherwise it likely should be left out to be swept during proofreading. It's more difficult to sweep the overall tone whilst maintaining cohesion.
Instead, focus on the content & flow of the work itself, and utilise the editor's note system to mark for later consideration any concerns regarding phrasing, naming, clarity, (narrative) style, grammar etc. It's much tidier now than in the pen & paper days.