Learn Hardcore Greek: Σε άλλες περιπτώσεις το πρόβλημα είναι μικρό, αλλά δεν θέλω ποτέ να δω φίλο μου στη φυλακή, γι’ αυτό του λέω να προσέχει τους κανόνες. - In other cases the problem is small, but I never want to see a friend of mine in prison, so I tell him to pay attention to the rules.

σε is a very common preposition that often corresponds to in / at / on / to in English.
άλλες = other, feminine plural, agreeing with
περιπτώσεις = cases / situations, feminine plural

So:

σε περιπτώσεις = in cases
σε άλλες περιπτώσεις = in other cases

Greek uses σε here in almost exactly the same way English uses in in in other cases.

Why is it το πρόβλημα είναι μικρό and not something like είναι μικρό το πρόβλημα? Is the word order fixed?

Both το πρόβλημα είναι μικρό and είναι μικρό το πρόβλημα are grammatically correct.

το πρόβλημα είναι μικρό is the neutral, most typical order: subject – verb – complement = the problem is small.
είναι μικρό το πρόβλημα puts a bit more emphasis on είναι μικρό (it is small, the problem), or contrasts it with something else. It sounds slightly more marked or stylistic.

So the word order is not completely fixed; Greek allows both orders, but the version in your sentence is the most straightforward one.

What’s the function of ποτέ in δεν θέλω ποτέ να δω? Why is it with δεν?

ποτέ means ever / never, depending on whether it’s used with negation:

With δεν: δεν … ποτέ = never
- δεν θέλω ποτέ να δω = I never want to see / I don’t ever want to see
Without δεν (in questions or conditionals): it usually means ever
- Θέλεις ποτέ να πας εκεί; = Do you ever want to go there?

In Greek, negative expressions like ποτέ (ever/never), κανείς (anyone/no one), etc., are normally used together with the negative particle δεν. This “double” marking is standard, not a mistake.

Word order can change:

δεν θέλω ποτέ να δω…
ποτέ δεν θέλω να δω…

Both mean I never want to see…, with only a slight difference in emphasis.

Why is να δω used instead of να βλέπω? What’s the difference?

Both forms come from the verb βλέπω (to see), but:

να δω is the aorist (perfective) subjunctive
να βλέπω is the present (imperfective) subjunctive

In this sentence:

δεν θέλω ποτέ να δω φίλο μου στη φυλακή
= I never want to see (even once) a friend of mine in prison.

The aorist (να δω) describes a single, complete event: seeing him there on some specific occasion.
If you said δεν θέλω ποτέ να βλέπω φίλο μου στη φυλακή, it would suggest something like:

I don’t want to be seeing my friend in prison (again and again / habitually)

which is possible, but a bit odd in this context. The natural idea is “not even once”, so να δω is the expected choice.

Why is it φίλο μου without an article? Why not τον φίλο μου?

φίλο μου here means “a friend of mine / any friend of mine”:

No article: φίλο μου
→ typically indefinite: a friend of mine, any friend of mine
With article: τον φίλο μου
→ usually definite / specific: my (particular) friend

In the sentence:

δεν θέλω ποτέ να δω φίλο μου στη φυλακή
= I never want to see a friend of mine in prison (any of my friends).

The focus is any friend at all, not one specific friend you have in mind, so leaving out the article is natural. You could say κανέναν φίλο μου (any friend of mine / not a single one), which would make that “any” nuance even stronger.

How does στη φυλακή work grammatically? What happened to σε την?

στη φυλακή comes from:

σε (in/at/to) + την φυλακή (the prison/jail, feminine singular)

Modern Greek regularly contracts σε + την:

σε την → στην (written as one word)

Then, there is a pronunciation/orthography rule:

The final -ν in την / στην is usually dropped before most consonants, including φ.
So στην φυλακή is normally written and pronounced στη φυλακή.

Meaning-wise:

στη φυλακή = in prison / in jail (with a definite article, but often used generically, like English in prison).

What does γι’ αυτό mean, and why is there an apostrophe?

γι’ αυτό means “so / therefore / that’s why”.

It comes from για αυτό:

για = for
αυτό = this / that

In fast, natural speech, για αυτό contracts to γι’ αυτό:

The vowel α of για is dropped before the vowel α of αυτό.
The apostrophe (’) shows this elision: γι’ is a shortened για.

In practice, γι’ αυτό is a fixed phrase meaning:

γι’ αυτό του λέω… = so I tell him… / that’s why I tell him…

What is του in γι’ αυτό του λέω? How is this different from saying λέω σε αυτόν?

του here is a clitic pronoun, 3rd person singular, genitive, used as an indirect object:

του λέω = I tell him / I say to him

In older Greek there was a dative case; in Modern Greek, the genitive form (like του, της, τους) usually replaces the dative for indirect objects.

You could say:

λέω σε αυτόν = I say to him (more emphatic, “to him in particular”)

but in natural everyday Greek, the clitic form is much more common:

του λέω να προσέχει… = I tell him to be careful…

Note also the position:

Clitic pronouns like του normally go before the verb: του λέω, not λέω του (except in some special cases like imperatives or infinitive-like forms).

Why is it του λέω να προσέχει and not να προσέξει? What’s the nuance?

Again, it’s about aspect:

να προσέχει = present (imperfective) subjunctive
→ focusing on ongoing / repeated carefulness
να προσέξει = aorist (perfective) subjunctive
→ focusing on a single act of being careful (or starting to be careful)

In this context:

να προσέχει τους κανόνες
= to (always) pay attention to / be careful about the rules, in general, as a habit or continuous behavior.

If you said του λέω να προσέξει τους κανόνες, it would sound more like:

I tell him to pay attention to the rules (this time / on this specific occasion).

Both are possible; the sentence you have stresses general, ongoing caution.

What does προσέχει mean here exactly? Does it mean “protect” or “pay attention”?

The verb προσέχω has several related meanings, depending on context:

to pay attention (to something)
to be careful (about something)
sometimes to look after / take care of someone or something

Here:

του λέω να προσέχει τους κανόνες
= I tell him to pay attention to the rules,
or I tell him to be careful about (respect/observe) the rules.

So the sense is pay attention / be careful, not “protect the rules”.

Why is it τους κανόνες and not just κανόνες without the article?

τους κανόνες is:

τους = definite article, masculine plural accusative
κανόνες = rules, masculine plural accusative

So τους κανόνες = the rules.

Using the article here is natural because we are referring to the known / existing rules of some system (e.g. the law, prison system, social rules, etc.), not just random, abstract “rules”.

Possible nuances:

να προσέχει τους κανόνες
= to be careful about the rules (that apply in that context)

If you said just να προσέχει κανόνες (no article), it would sound odd or incomplete, almost like to be careful rules; normally, a direct object like this uses the article unless you have a special reason not to.

Do the adjectives and nouns agree in gender and number in Σε άλλες περιπτώσεις το πρόβλημα είναι μικρό? How?

Yes, Greek requires agreement of adjectives with the nouns they describe:

άλλες (other) – feminine, plural, nominative
περιπτώσεις (cases) – feminine, plural, nominative
→ They agree: σε άλλες περιπτώσεις.

For το πρόβλημα είναι μικρό:

το πρόβλημα – neuter, singular, nominative
μικρό – neuter, singular, nominative (adjective used as predicate)

So μικρό agrees with πρόβλημα in gender (neuter) and number (singular).

Agreement like this is a core feature of Greek grammar and one of the main differences from English, which doesn’t change adjective form in this way.