Learn Hardcore Greek: Ο δικός μου χαρακτήρας είναι πιο νευρικός, και μερικές φορές παραπονιέμαι χωρίς σοβαρό πρόβλημα. - My own character is more nervous, and sometimes I complain without a serious problem.

Ο χαρακτήρας μου = my character (neutral, the normal way to say it).
Ο δικός μου χαρακτήρας = my own character / my character (as opposed to someone else’s).

δικός, δική, δικό is the “strong/independent” possessive. It adds emphasis or contrast, often implying:

Ο δικός μου χαρακτήρας → my character (as opposed to yours / his / theirs).
Context: maybe we are comparing my character with someone else’s.

Without any contrast or emphasis, a Greek speaker would more often say Ο χαρακτήρας μου είναι πιο νευρικός.

Why is there an article Ο before χαρακτήρας? Could we say just Δικός μου χαρακτήρας είναι…?

In standard Greek, you normally need the definite article before a singular countable noun used as a subject:

Ο χαρακτήρας μου είναι… – literally the character of mine is… → my character is…

You cannot normally drop the article here, so:

❌ Δικός μου χαρακτήρας είναι… sounds wrong/very marked.
✅ Ο δικός μου χαρακτήρας είναι…

Greek uses the definite article far more than English, even with things that in English don’t take the (e.g. Ο πατέρας μου, Η δουλειά μου, Η υγεία μου).

Why does δικός end in -ός here? How does it agree with χαρακτήρας?

χαρακτήρας is:

masculine
singular
nominative (subject of the verb)

So δικός must match it in gender, number, and case:

masculine → δικός
singular → δικός
nominative → δικός

If the noun were feminine or neuter, δικός would change:

Η δική μου φίλη – my (female) friend
Το δικό μου αυτοκίνητο – my car

In your sentence: Ο δικός μου χαρακτήρας → all elements are masculine singular nominative and agree with each other.

What exactly does πιο do in πιο νευρικός? How is “more nervous” formed in Greek?

πιο is the basic word for “more” when forming a comparative of most adjectives:

νευρικός → πιο νευρικός = more nervous
όμορφος → πιο όμορφος = more beautiful
δύσκολος → πιο δύσκολος = more difficult

So the structure is:

πιο + adjective = “more + adjective”

There are also some irregular/synthetic comparatives (e.g. καλός → καλύτερος = good → better), but νευρικός uses the regular πιο pattern.

There is no “than…” after πιο νευρικός. Is that okay? Isn’t a comparison incomplete?

It is fine and very natural in Greek, just like in English:

“My character is more nervous.” (We understand “than other people’s / than it used to be”, etc.)
Ο (δικός μου) χαρακτήρας είναι πιο νευρικός.

If you do want to specify the comparison, you use από (or παρά in some cases):

Ο χαρακτήρας μου είναι πιο νευρικός από τον δικό σου.
“My character is more nervous than yours.”

Why is the comma before και there? Is it required in Greek?

You can write it:

…είναι πιο νευρικός, και μερικές φορές παραπονιέμαι…

or without the comma:

…είναι πιο νευρικός και μερικές φορές παραπονιέμαι…

Both are acceptable. The comma is optional and gives a slightly stronger pause, as if separating the two parts more clearly:

είναι πιο νευρικός (statement about character)
μερικές φορές παραπονιέμαι… (extra information about a habit)

In everyday writing, many Greeks would probably omit the comma here.

What does μερικές φορές literally mean, and where can it appear in the sentence?

μερικές φορές literally = “a few times”, but idiomatically it means sometimes.

In terms of position, you can put it:

At the beginning:
Μερικές φορές παραπονιέμαι χωρίς σοβαρό πρόβλημα.
Between subject and verb:
Εγώ μερικές φορές παραπονιέμαι…
After the verb (less common, but possible):
Παραπονιέμαι μερικές φορές… (slightly different rhythm/emphasis)

The most neutral, common choices are:

Μερικές φορές παραπονιέμαι…
Και μερικές φορές παραπονιέμαι…

What kind of verb is παραπονιέμαι? Why does it end in -ομαι?

παραπονιέμαι is a mediopassive (often called “reflexive-like”) verb in the present tense. Many Greek verbs appear only in this form in daily use.

Present tense (indicative):

(εγώ) παραπονιέμαι – I complain
(εσύ) παραπονιέσαι
(αυτός/αυτή/αυτό) παραπονιέται
(εμείς) παραπονούμαστε / παραπονιόμαστε
(εσείς) παραπονιέστε / παραπονιόσαστε
(αυτοί/αυτές/αυτά) παραπονιούνται

It is not used actively as παραπονίζω etc. in normal modern Greek. The -ομαι ending is just the standard mediopassive ending.

Do I need to add για after παραπονιέμαι? For example παραπονιέμαι για κάτι?

You can add για, but you don’t have to.

With για you specify what you complain about:
Παραπονιέμαι για τη δουλειά μου. – I complain about my job.
Without για, you just say that you complain in general:
Μερικές φορές παραπονιέμαι. – Sometimes I complain.

In your sentence, χωρίς σοβαρό πρόβλημα explains the situation enough, so για is not needed.

Why is πρόβλημα in the form σοβαρό πρόβλημα (with -ό)?

πρόβλημα is:

neuter
singular
accusative (object of the preposition χωρίς)

The adjective σοβαρός must agree and take:

neuter → σοβαρό
singular → σοβαρό
accusative → σοβαρό (same as nominative in neuter singular)

So:

nominative: το σοβαρό πρόβλημα – the serious problem (as subject)
accusative: χωρίς σοβαρό πρόβλημα – without (a) serious problem

All prepositions in modern Greek (including χωρίς) normally require the accusative case.

Why is there no article before σοβαρό πρόβλημα? Why not χωρίς ένα σοβαρό πρόβλημα?

After χωρίς (“without”), it is very common in Greek to drop the article when you speak in a general/indefinite sense:

χωρίς σοβαρό πρόβλημα – without serious problem / without any serious problem
χωρίς χρήματα – without money
χωρίς φαγητό – without food

You can say χωρίς ένα σοβαρό πρόβλημα, but it sounds more like:

“without one particular serious problem” (more specific, a bit heavier)

In your sentence, χωρίς σοβαρό πρόβλημα is the most natural choice.

Does νευρικός mean “nervous” as in “having a sensitive nervous system” or “easily irritated”? Is it the same as αγχωμένος?

In modern everyday Greek:

νευρικός usually means easily irritated / edgy / jumpy / touchy.
Example: Είναι πολύ νευρικός σήμερα. – He is very on edge today.
αγχωμένος means stressed / anxious (full of stress).
Example: Είμαι αγχωμένος για τις εξετάσεις. – I’m stressed about the exams.

So πιο νευρικός might suggest:

more irritable / more quick-tempered / more on edge

It can sometimes overlap with “nervous” (anxious), but many Greeks would choose αγχωμένος for “anxious” and νευρικός more for bad temper or restlessness.

Could I say Ο χαρακτήρας μου είναι πιο νευρικός without δικός? Would that change the meaning?

Yes, and that is actually the most neutral version:

Ο χαρακτήρας μου είναι πιο νευρικός…

Compared to:

Ο δικός μου χαρακτήρας είναι πιο νευρικός…

Differences:

Ο χαρακτήρας μου – simple, neutral “my character”.
Ο δικός μου χαρακτήρας – emphasizes my in contrast with another person’s character or what is expected.

If there is no contrast in the context, most speakers would naturally say Ο χαρακτήρας μου.

Can the word order around πιο νευρικός change? For example, could I say είναι νευρικός πιο?

No, είναι νευρικός πιο is ungrammatical. In Greek, πιο normally comes before the adjective:

✅ είναι πιο νευρικός
❌ είναι νευρικός πιο

You can move the whole phrase πιο νευρικός around relative to other elements (subject, extra adverbs), but πιο must stay directly in front of the adjective it modifies.