Learn Hardcore Portuguese (Portugal): O irmão dela era muito tímido em criança, mas agora é mais aberto. - Her brother was very shy as a child, but now he is more open.

de + ela → dela is the correct contracted form. irmão de ela is wrong.
o irmão dela literally means the brother of her / her brother.
In European Portuguese, dele / dela / deles / delas is very common to avoid ambiguity with seu / sua / seus / suas, which can mean his, her, their, your (formal).
- o seu irmão could mean your brother or his/her brother, depending on context.
- o irmão dela is always her brother, unambiguous.
The article o is needed: you normally say o irmão dela, not just irmão dela, when you’re talking about a specific person.

Why is the past tense era used here and not foi?

Both era and foi are past forms of ser, but they’re different tenses:
- era = imperfect (ongoing, habitual, descriptive in the past)
- foi = preterite (completed event or state, seen as a finished block)
era muito tímido em criança describes a general, long-lasting characteristic of his childhood, not a single event, so the imperfect (era) is the natural choice.
foi muito tímido em criança is possible, but sounds more like you’re treating that timidity as a closed chapter of life, a bit more “from X to Y, he was shy.” The neutral, most idiomatic option here is era.

Why is it era in the first part and é in the second part (mas agora é mais aberto)?

First clause: era muito tímido em criança – talking about a state in the past.
Second clause: agora é mais aberto – talking about his state now, in the present.
So the contrast is: past (era) vs present (é).
Using é suggests this new, more open personality is a current, relatively stable trait.

Why is ser used and not estar, especially in agora é mais aberto?

ser is used for more permanent or defining characteristics (personality, identity).
estar is for temporary states or conditions.
Shyness vs openness are usually treated as personality traits, so Portuguese uses ser:
- Ele é tímido. / Ele é aberto.
Ele está mais aberto would imply he is behaving more open for now, maybe due to the situation, not necessarily a lasting personality change.
In this sentence, the idea is that his character changed over time, so ser fits.

What exactly does em criança mean, and could I say it differently?

em criança means when (he was) a child / as a child.
It’s an idiomatic, very common expression in European Portuguese.
Natural alternatives include:
- quando era criança – when he was a child
- em pequeno (PT‑PT) – when he was little (male)
- na infância – in (his) childhood
All of these would work in this sentence; em criança is just concise and idiomatic.

Why is criança feminine if we’re talking about o irmão (a male)?

In Portuguese, criança is a grammatically feminine noun: a criança.
Its grammatical gender does not change depending on whether the child is a boy or a girl.
So you say:
- uma criança tímida, even if the child is male.
In em criança, there’s no article, but the noun itself is still feminine; it just doesn’t matter here because there’s no adjective agreeing with it.

Why is it tímido and not tímida or tímidos?

Adjectives agree with the noun they describe in gender and number.
The adjective tímido is describing o irmão:
- irmão is masculine singular → tímido (masculine singular).
Other forms would be:
- irmã tímida – shy sister (feminine singular)
- irmãos tímidos – shy brothers (masculine plural or mixed group)
- irmãs tímidas – shy sisters (feminine plural).

What does mais aberto really mean here? Literally “more open”?

Literally, aberto means open (e.g. a porta está aberta – the door is open).
When used about a person, ser aberto means to be open / outgoing / not shy.
mais aberto here means more open (than before), i.e. less shy, more sociable and communicative.
Near synonyms in this context: mais extrovertido, mais sociável, mais comunicativo.

Could I say menos tímido instead of mais aberto?

Grammatically, yes: …mas agora é menos tímido is correct.
menos tímido focuses on reducing the same quality (shyness).
mais aberto suggests not just “less shy”, but a positive new trait (more outgoing, more open to people/experiences).
So the original version emphasizes a change of personality, not just a decrease of shyness.

Can the word order change, like Em criança, o irmão dela era muito tímido?

Yes, that’s perfectly correct:
- Em criança, o irmão dela era muito tímido, mas agora é mais aberto.
Time expressions such as em criança, quando era criança, na infância can appear:
- at the beginning: Em criança, ele era…
- after the verb: Ele era… em criança.
Moving em criança to the front slightly emphasizes the time frame, but the meaning is the same.

Is the comma before mas necessary?

Yes, in this sentence you need a comma before mas.
Mas is a coordinating conjunction similar to English but, and when it connects two clauses, it’s normally preceded by a comma:
- …era muito tímido em criança, mas agora é mais aberto.
You might omit the comma if mas is just linking two short words or phrases, but between full clauses it’s standard to use it.

Why isn’t the pronoun ele used? Why not O irmão dela, ele era muito tímido…?

Portuguese is a pro‑drop language: subject pronouns are often omitted when the subject is clear from context or verb ending.
Here the subject is clearly o irmão dela, and the verb forms (era, é) already reflect 3rd person singular, so adding ele is unnecessary.
O irmão dela, ele era muito tímido… is possible in very colloquial or emphatic speech, but in standard written Portuguese it would sound redundant or stylistically clumsy.