English language I.: I | me

I | me

I am mostly forced to rely on my school English which sometimes leaves me wondering.

Very often I encounter an ‘I’ where I expect to encounter a ‘me’.

Can someone explain the rules to me?

This is not especially the case with works of nonprofessional authors but in professional novels too.

In German you got the words [mir] and [mich].
There is an aphorism: Mit mir und mich vertue ich mir nicht, das kommt bei mich nicht vor.
You don’t need to tell me that in the sentence both words are used in the wrong place.

Some people (incorrectly) use I as an object instead of me because somewhere in school they remember hearing you should never use I after a preposition., but this is not the case.

John and I ate the fish - I is part of the subject (this is where people remember that rule, because sometimes children will say "John and me ate the fish", which is incorrect).

The fish ate John and me - the fish is the subject, and the first person speaker is part of the object of the verb. So using German as an analogue:

Ich = I (nominative case)
Mich or mir = me (accusative/dative)

And don't get me started on people misusing "myself" as a subject or an object, rather than as a reflexive or intensive pronoun.

To add to the confusion, so many today use something like 'me and John' went to the shop when they should say 'John and I went to the shop', putting the other person before yourself. So, 'the fish ate John and me' is fine, 'the fish ate me and John' is not.

@ mianders

It's the same in German and we got an aphorism for it. Translated it would be something like "The donkey names himself first." Since we don't want to be donkeys we mostly say 'The fish ate John and me.'

John and you come across a lion.
What would you do?
I: I would put on my sneakers
John: That won't allow you to escape the lion.
I: True, but I can run faster than you.
Result: The lion ate John and me.
Firstly It allows you to follow rules, but it won't save you.
Secondly you won't be able to break the rules anyway. Once the lion has sated his hunger you won't say anything anymore.