Learn Hardcore Greek: Η τσάντα μου σήμερα είναι πολύ βαριά, θα έπρεπε να είχα πάρει την πιο ελαφριά. - My bag today is very heavy; I should have taken the lighter one.

Here, the neutral, everyday form is used, so the word order η τσάντα μου is completely standard and much more common than putting μου before the noun.

Why is the adjective βαριά in the feminine form?

Adjectives in Greek agree with the noun they describe in:

gender (masculine / feminine / neuter)
number (singular / plural)
case (nominative / etc.)

Τσάντα is a feminine noun:

η τσάντα (the bag) – feminine, singular, nominative

The adjective βαρύς (heavy) has feminine βαριά.
So we get:

η τσάντα μου είναι πολύ βαριά
= η (feminine) τσάντα (feminine) … βαριά (feminine)

Everything matches in gender and number: η τσάντα (fem. sg.) → βαριά (fem. sg.).

Could I also say Η τσάντα μου είναι πολύ βαριά σήμερα? Does word order with σήμερα matter?

Yes, you can absolutely say:

Η τσάντα μου είναι πολύ βαριά σήμερα.

Both:

Η τσάντα μου σήμερα είναι πολύ βαριά
Η τσάντα μου είναι πολύ βαριά σήμερα

are correct and natural.

The difference is only a slight nuance in emphasis:

Η τσάντα μου σήμερα είναι πολύ βαριά
subtly highlights σήμερα (today: as opposed to other days).
Η τσάντα μου είναι πολύ βαριά σήμερα
sounds a bit more neutral, like standard English word order.

In everyday speech, both orders are common; context and intonation give the real emphasis.

Why is there a comma before θα έπρεπε? Is this one sentence or two?

In Greek, it is quite common to link two closely related clauses with a comma, even when in English we might prefer a full stop or a connector like so.

Here we have:

Η τσάντα μου σήμερα είναι πολύ βαριά,
θα έπρεπε να είχα πάρει την πιο ελαφριά.

It’s basically:

My bag is very heavy today, I should have taken the lighter one.

You could also write it as two sentences:

Η τσάντα μου σήμερα είναι πολύ βαριά. Θα έπρεπε να είχα πάρει την πιο ελαφριά.

Both are acceptable in modern Greek punctuation. The comma signals a close link (cause → regret) between the two ideas.

What exactly does θα έπρεπε να είχα πάρει mean, and how is it formed?

Θα έπρεπε να είχα πάρει literally combines:

θα (modal particle, often marking a conditional or future)
έπρεπε (past of πρέπει = must / should)
να είχα πάρει (a form like a past perfect after να)

Together it means:

I should have taken (but I didn’t)
It expresses regret about a past, unreal action.

Structurally:

έπρεπε να πάρω = I had to / I should take
θα έπρεπε να πάρω = I would/should (in general / in theory) take
θα έπρεπε να είχα πάρει = I should have taken (unfulfilled obligation, regret)

In everyday terms, you can treat θα έπρεπε να είχα πάρει as the natural Greek way to say I should have taken.

What is the difference between Έπρεπε να πάρω and Θα έπρεπε να είχα πάρει?

They are close, but not identical in nuance.

Έπρεπε να πάρω την πιο ελαφριά.
Literally: I had to / I should take the lighter one.
Depending on context, it can mean:
- I was supposed to take it (and maybe I did, maybe I didn’t), or
- I should have taken it (regret), especially if the context makes that clear.
Θα έπρεπε να είχα πάρει την πιο ελαφριά.
Stronger sense of unfulfilled obligation + regret:
- I should have taken the lighter one (but I didn’t).

So:

Έπρεπε να πάρω… = more neutral past necessity / advice.
Θα έπρεπε να είχα πάρει… = clearly a missed action, with regret.

Why do we use είχα πάρει (had taken) after να? Could we say να πάρω instead?

After να, Greek can use various verb forms, including forms that look like past tenses, to express different time and mood nuances.

Here:

να είχα πάρει is used together with θα έπρεπε to express a past action that did not happen (I should have taken).

If you said:

Θα έπρεπε να πάρω την πιο ελαφριά.

this usually sounds like:

I should (now/in general) take the lighter one
or
I would have to take the lighter one (depending on context).

To clearly capture I should have taken (but I didn’t), Greek prefers:

Θα έπρεπε να είχα πάρει…

So να είχα πάρει fits the idea of a past, unreal, regretted action much better than να πάρω here.

Why do we say την πιο ελαφριά with a definite article την, even though English says a lighter one or the lighter one without repeating bag?

In Greek, when an adjective is used as a noun (standing for a noun that is understood), it almost always takes the definite article.

Here, την πιο ελαφριά literally means:

the lighter (one) [bag]

The noun τσάντα is omitted but understood from context, and the article την:

marks gender, number, and case (feminine, singular, accusative)
shows that we are talking about a specific member of a known set (from the bags available).

So:

να είχα πάρει την πιο ελαφριά (τσάντα)
= to have taken the lighter (bag)

Using την is natural and required; without it (να είχα πάρει πιο ελαφριά) the phrase would sound incomplete or incorrect here.

Is πιο ελαφριά comparative or superlative? And can I say ελαφρύτερη instead?

Πιο ελαφριά is a comparative phrase:

πιο ελαφριά = lighter
(literally: more light)

In Greek you often have two ways to form the comparative:

Analytic: πιο ελαφριά (more light)
Synthetic: ελαφρύτερη

So:

την πιο ελαφριά (τσάντα)
την ελαφρύτερη (τσάντα)

Both mean the lighter bag (among some other, heavier one(s)).
In this sentence, την πιο ελαφριά and την ελαφρύτερη are both correct and natural.

Why don’t we say εγώ in θα έπρεπε να είχα πάρει? Where is the subject?

In Greek, subject pronouns (εγώ, εσύ, αυτός etc.) are usually omitted because the verb ending already tells you who the subject is.

θα έπρεπε να είχα πάρει
The ending -α in είχα πάρει here, together with context and the whole phrase, indicates 1st person singular: I.

If you add εγώ:

Εγώ θα έπρεπε να είχα πάρει την πιο ελαφριά.

it adds emphasis on I:

I should have taken the lighter one (as opposed to someone else).

So the basic, unmarked version naturally drops εγώ.

What does πολύ add in είναι πολύ βαριά? Could we use something stronger?

Πολύ is an intensifier meaning very or really:

είναι πολύ βαριά = it is very heavy / really heavy.

A stronger, more emphatic version is:

είναι πάρα πολύ βαριά
= it is extremely / really, really heavy.

So the pattern is:

είναι βαριά = it is heavy
είναι πολύ βαριά = it is very heavy
είναι πάρα πολύ βαριά = it is extremely heavy