Vaya donde vaya, mi prima siempre lleva una botella de agua y un sombrero.

This is a very common Spanish pattern: verb + donde/como/cuando + same verb.

So Vaya donde vaya means something like wherever she goes.

It is not saying the same thing twice for no reason. The repetition creates an indefinite / no matter where meaning:

• vaya donde vaya = wherever she goes
• haga lo que haga = whatever she does
• digan lo que digan = whatever they say

It is a fixed, natural structure in Spanish.

Vaya is the present subjunctive of ir.

The subjunctive is used here because the sentence is not talking about one specific destination. It expresses an indefinite idea: no matter where she goes.

Compare:

• Va donde trabaja su hermano. = She goes to where her brother works.
  
  • specific place, so indicative
• Vaya donde vaya, ... = Wherever she goes, ...
  
  • indefinite / general, so subjunctive

This repeated pattern almost always uses the subjunctive.

Because va donde va would sound literal and odd here, like she goes where she goes. It does not naturally give the meaning wherever she goes.

To express wherever, Spanish normally uses this subjunctive repetition:

• vaya donde vaya
• not usually va donde va

So the subjunctive is essential to the idiomatic meaning.

Because donde here is a relative word, not a direct or indirect question.

Use dónde with an accent in questions or exclamations:

• ¿Dónde está mi prima?
• No sé dónde está.

Use donde without an accent in relative clauses like this one:

• Voy donde tú vas.
• Vaya donde vaya...

A helpful shortcut:

• question word -> usually accented
• relative/linking word -> usually not accented

Yes, you may sometimes hear adonde or a donde with verbs of movement such as ir.

Possible versions:

• Vaya donde vaya
• Vaya adonde vaya
• Vaya a donde vaya

In modern everyday Spanish, especially in many contexts, donde is very common even with movement verbs.

Very roughly:

• donde can mean where
• adonde / a donde can emphasize to where

But in this sentence, donde is perfectly natural.

Because Vaya donde vaya is an introductory subordinate clause. In English, we also often separate this kind of phrase:

• Wherever she goes, my cousin always carries...

In Spanish, that comma is normal and helps show the structure:

• introductory clause: Vaya donde vaya,
• main clause: mi prima siempre lleva...

Because Spanish usually drops subject pronouns when the verb already makes the subject clear.

Here:

• lleva already tells you it is he/she/it form
• mi prima is explicitly stated anyway

So ella would be unnecessary:

• Vaya donde vaya, mi prima siempre lleva... = natural
• Vaya donde vaya, ella siempre lleva... = possible, but only if you want emphasis or contrast

Spanish often avoids pronouns when they are not needed.

Here lleva means carries / takes with her / has on her.

The verb llevar is very broad. It can mean:

• to carry
• to take
• to wear
• to have with you

In this sentence, because of una botella de agua y un sombrero, the broad idea is that she always has these things with her.

So lleva is more natural than translating it with just one English verb in every context.

It can mean either, depending on context.

• llevar un sombrero often means to wear a hat
• but in a sentence like this, alongside una botella de agua, it can also suggest she always has a hat with her

So the sentence may be understood as:

• she always carries a bottle of water and a hat, or
• she always has a bottle of water and is wearing / carrying a hat

The exact nuance depends on context, but the general idea is clear: these are things she consistently keeps with her.

Because llevar and traer are not the same.

• llevar = to take / carry something away or along
• traer = to bring something toward the speaker or another reference point

Here the sentence is describing what she habitually has with her, not what she brings to here, so llevar fits much better.

That is a very normal position for siempre.

• mi prima siempre lleva... = natural
• mi prima lleva siempre... = also possible, but usually a bit less neutral in many contexts

Spanish adverbs like siempre, nunca, ya, también often appear before the conjugated verb.

Because una botella de agua is a more specific noun phrase: a bottle of water.

The sentence is not just saying she carries water in a general sense. It says she carries a bottle of water.

Structure:

• botella = the container
• de agua = what is inside / what kind of bottle

This noun + de + noun pattern is extremely common:

• una taza de café
• un vaso de leche
• una botella de agua

Because de agua means of water in a descriptive sense, not of the water.

• una botella de agua = a bottle of water
• la botella del agua = the bottle of the water

The second version would only make sense in a very specific context where the water has already been identified.

So here de agua is the normal expression.

Because sombrero is a masculine noun, so it takes un in the singular:

• un sombrero
• el sombrero

Spanish articles must agree with the noun in gender and number.

Because botella is a feminine noun, and feminine singular nouns usually take:

• una = indefinite article
• la = definite article

So:

• una botella
• la botella

This is one of the most regular patterns in Spanish.

Because the sentence is talking about the kinds of things she typically carries, not about one specifically identified bottle and one specifically identified hat.

• una botella de agua y un sombrero = a bottle of water and a hat
• la botella de agua y el sombrero would sound like specific known items

The indefinite articles are the natural choice for a general habit.

Yes, if the context already made the subject clear.

For example:

• Vaya donde vaya, siempre lleva una botella de agua y un sombrero.

That would be perfectly grammatical.

But mi prima is included here to make the subject explicit and clear.

Yes. Even though mi prima only appears in the main clause, we understand that the same person is the subject of both verbs:

• [Ella] vaya donde vaya
• mi prima siempre lleva...

Spanish often leaves the subject implied in subordinate clauses when it is obvious.

It is a kind of concessive / free relative expression.

In practical learner terms, it means:

• no matter where she goes
• wherever she goes

It sets up a contrast between changing circumstances and a constant habit:

• the place may change
• her habit does not change

That is why the main clause uses siempre: no matter the place, she always does the same thing.

Because the main clause states a habitual fact about your cousin:

• mi prima siempre lleva...

This is a normal use of the present indicative in Spanish, just like English uses the simple present for habits:

• She always carries...

So the sentence combines:

• subjunctive in the introductory wherever clause
• indicative in the main factual statement

It is completely normal Spanish. The pattern vaya donde vaya is idiomatic and widely used, both in speech and writing.

It may sound slightly more elegant than a very basic alternative, but it is not unusually formal or literary.

Similar everyday expressions include:

• Pase lo que pase = Whatever happens
• Sea como sea = Be that as it may / Anyway
• Esté donde esté = Wherever he/she is

Yes, very often.

Examples:

• Haga lo que haga, la apoyaré. = Whatever she does, I’ll support her.
• Diga lo que diga, no le creerán. = Whatever she says, they won’t believe her.
• Esté donde esté, te llamaré. = Wherever I am, I’ll call you.
• Venga cuando venga, lo recibiremos. = Whenever he comes, we’ll welcome him.

This is a very useful pattern to learn because it appears often and sounds very natural.