Learn Hardcore Greek: Με τους φίλους μου μιλάω με άτυπο τρόπο, ο οποίος είναι πιο φυσικός για εμάς. - With my friends I speak in an informal way, which is more natural for us.

Μιλάω με τους φίλους μου – neutral, normal order: I talk with my friends…
Με τους φίλους μου μιλάω – fronting με τους φίλους μου gives it more emphasis: With my friends I speak… (contrasting with other people, e.g. not with colleagues).

Grammatically they are both fine; the original sentence just emphasizes with my friends.

Where is the word “I” in the sentence? Why is there no separate word for I?

In Greek, the personal subject pronoun is usually dropped, because the verb ending already shows the person:

μιλάω = I speak (1st person singular)
μιλάς = you speak
μιλάει / μιλά = he/she speaks

So μιλάω already means I speak, and adding εγώ is only for emphasis:

Εγώ μιλάω με τους φίλους μου... – I (as opposed to someone else) talk with my friends…

In the sentence given, εγώ is understood but not written.

What is the difference between μιλάω and μιλώ?

They are just two forms of the same verb:

μιλάω – more colloquial, very common in everyday speech and writing
μιλώ – a bit more formal or neutral, preferred in very formal writing, but also used in normal speech

Both are correct. You could say:

Με τους φίλους μου μιλάω...
Με τους φίλους μου μιλώ...

with no real change in meaning.

Why is it μιλάω με τους φίλους μου and not μιλάω τους φίλους μου?

The verb μιλάω (to speak, to talk) in Greek usually needs a preposition when you specify who you speak with/to:

μιλάω με κάποιον – I talk with someone
μιλάω σε κάποιον – I talk to someone

So you don’t say μιλάω τους φίλους μου (that would be wrong). You must use:

μιλάω με τους φίλους μου – I talk with my friends
or
μιλάω στους φίλους μου – I talk to my friends

In your sentence, με emphasizes the idea of interaction / conversation with them.

Why do we say με άτυπο τρόπο and not just use an adverb, like άτυπα?

Both are possible, but there is a nuance:

με άτυπο τρόπο – literally in an informal way / manner. Slightly more explicit or careful, can sound a bit more formal or explanatory.
άτυπα – adverb: informally. Shorter and very natural in speech.

So you could also say:

Με τους φίλους μου μιλάω άτυπα, που είναι πιο φυσικό για εμάς.

The original με άτυπο τρόπο matches the English structure in an informal way and sounds a bit more “spelled out.”

Why is άτυπο and not άτυπα in με άτυπο τρόπο?

Because άτυπο is agreeing with τρόπο:

ο τρόπος – masculine, singular
In accusative: τον τρόπο

The adjective άτυπος (informal) must agree in gender, number, and case:

άτυπος τρόπος – nominative
άτυπο τρόπο – accusative (after με)

So με άτυπο τρόπο is: with/in an informal way.

If you say άτυπα on its own, that’s an adverb, not an adjective:

Μιλάω άτυπα. – I speak informally.

What is ο οποίος here, and how is it different from που?

ο οποίος is a relative pronoun meaning roughly who / which / that. It introduces a relative clause that refers back to a noun, here τρόπο:

...με άτυπο τρόπο, ο οποίος είναι πιο φυσικός για εμάς.
= ...in an informal way, which is more natural for us.

Differences from που:

Formality
- ο οποίος is more formal / careful.
- που is more colloquial and very common in everyday speech.
Agreement
- ο οποίος changes form to agree with the noun in gender, number, and case.
- που is invariable (it doesn’t change).

You could also say:

...με άτυπο τρόπο, που είναι πιο φυσικός για εμάς.

This is very natural in spoken Greek and in informal writing. The meaning is the same.

Why is it ο οποίος and not που if Greek people usually say που?

In many real-life contexts, που would indeed be more common:

Με τους φίλους μου μιλάω με άτυπο τρόπο, που είναι πιο φυσικός για εμάς.

However, ο οποίος is preferred when:

the style is a bit more formal or written,
the speaker wants to sound more precise or careful,
or in teaching materials, where they also want to show the full paradigm (ο οποίος, η οποία, το οποίο, etc.).

So the choice of ο οποίος here is more about style, not correctness. Both are grammatically fine.

Why is it ο οποίος είναι πιο φυσικός and not ο οποίος είναι πιο φυσικό?

The relative pronoun ο οποίος and the adjective φυσικός must agree with the noun τρόπο:

τρόπος – masculine, singular, nominative
So the relative pronoun is ο οποίος (masculine, singular, nominative)
The adjective in the predicate position must also be masculine singular: φυσικός

Hence:

...τρόπο, ο οποίος είναι πιο φυσικός...

If the noun were feminine, it would change:

με άτυπη μορφή, η οποία είναι πιο φυσική...
(μορφή is feminine, so η οποία, φυσική.)

How does the comparative πιο φυσικός work? Is there another way to say more natural in Greek?

Greek has two ways to form comparatives:

With πιο + adjective (very common):
- πιο φυσικός – more natural
- πιο όμορφος – more beautiful
With a synthetic comparative ending (more formal / less common for some adjectives):
- φυσικότερος – more natural
- ομορφότερος – more beautiful

In everyday Greek, πιο φυσικός is by far the most usual. φυσικότερος sounds more formal, literary, or a bit old-fashioned. Both are correct, but πιο φυσικός is what you will normally say.

Why is it για εμάς and not για εμείς? And when do I use εμείς vs εμάς vs μας?

εμείς and εμάς are different cases of the same pronoun (we/us), and μας is the clitic/weak form:

εμείς – nominative (subject): we
- Εμείς μιλάμε. – We speak.
εμάς – accusative/genitive (strong form): us (stressed or after prepositions)
- για εμάς – for us
- από εμάς – from us
- μας αγαπούν εμάς. – They love us (with emphasis on us).
μας – weak form (usual unstressed us/our):
- μας μιλάνε. – They talk to us.
- οι φίλοι μας – our friends.

After a preposition like για, you use the strong form εμάς:

για εμάς – for us

για εμείς is ungrammatical.