Learn Hardcore Spanish (Spain): Aunque parezco tímida, mi carácter es fuerte cuando algo me parece injusto. - Although I seem shy, my character is strong when something seems unfair to me.

Aunque parezco tímida… = Although I seem / I come across as shy… (how others perceive me)
Aunque soy tímida… = Although I am shy… (I really am shy as part of my character)

In the original sentence, the contrast is between how I seem on the outside and how I really am inside, so parezco fits better.

Why is there no yo? Could I say Aunque yo parezco tímida?

Spanish usually drops subject pronouns because the verb ending already shows the subject:

parezco = I seem (1st person singular), so yo is not needed.

You can say Aunque yo parezco tímida, but that adds emphasis, a bit like:

Although *I seem shy… (as opposed to someone else).*

In neutral speech, Aunque parezco tímida… is more natural.

What does aunque do here, and how is it different from pero?

Aunque introduces a concession (something that might make you expect the opposite of what follows):

Aunque parezco tímida, mi carácter es fuerte…
Although / even though I seem shy, my character is strong…

You could also say:

Parezco tímida, pero mi carácter es fuerte…
I seem shy, but my character is strong…

Differences:

aunque goes inside the first clause and makes that whole clause concessive.
pero just links two full statements that contrast.

Both are correct here; aunque sounds a bit more formal or “written” than pero in this structure.

Why is it aunque parezco and not aunque parezca? When do you use the subjunctive after aunque?

After aunque, you use:

Indicative (here: parezco) for a real, known fact:
- Aunque parezco tímida…
  = Although I (indeed) seem shy…
Subjunctive for something hypothetical, unknown, or not presented as a fact:
- Aunque parezca tímida, habla mucho.
  = Even if she might seem shy, she talks a lot.

In your sentence, the speaker accepts as true that they seem shy, so parezco (indicative) is correct.

What exactly does carácter mean here, and why does it have an accent?

Carácter (with an accent) is masculine: el carácter, mi carácter.

Meaning here: temperament, character, inner nature, especially about being strong‑willed or firm.

mi carácter es fuerte = my character/temperament is strong

In Spain, people often say:

Tiene mucho carácter. = She/he is very strong‑willed / has a strong personality.

The accent in carácter marks the stressed syllable: ca‑rác‑ter.

Is mi carácter es fuerte different from tengo un carácter fuerte?

Both are correct and very natural, with almost the same meaning:

Mi carácter es fuerte.
Tengo un carácter fuerte.

Nuance:

tengo un carácter fuerte is slightly more idiomatic as a fixed expression for describing personality.
mi carácter es fuerte sounds a bit more descriptive or “spelled out”, but it’s perfectly normal Spanish.

You can use either in this sentence.

Why is cuando followed by the present tense (me parece) instead of a future tense?

Spanish often uses the present tense after cuando to talk about:

Habitual or general situations
Future situations (where English would use “will”)

Here it’s a general, habitual situation:

…cuando algo me parece injusto.
= …when something seems unfair to me (in general / whenever that happens).

Using parecerá would be unusual here. The Spanish present covers what English expresses with “when something seems / whenever something seems / when something will seem” depending on context.

What is going on in algo me parece injusto? Why do we need me, and why that word order?

Parecer here works like gustar:

algo = the grammatical subject (something)
me = indirect object pronoun (to me)
parece injusto = seems unfair

Literally: “something seems unfair to me.”

So:

Algo me parece injusto. = Something seems unfair to me.

Word order:

The most neutral is Algo me parece injusto or A mí algo me parece injusto (with emphasis on to me).
You can say me parece algo injusto, but then algo tends to mean “somewhat / a bit”, so it becomes: it seems a bit unfair, which is a different meaning.

Why is it injusto and not injusta?

Adjectives must agree with the thing they describe. Here, injusto agrees with algo:

algo is treated as masculine singular for adjective agreement.
So we say: algo injusto, algo raro, algo bonito, etc.

That’s why it’s injusto (masculine singular), not injusta.

Why tímida with an -a? What if the speaker is male?

Tímido / tímida agrees with the gender of the person:

Female speaker: parezco tímida
Male speaker: parezco tímido

In Spanish, most adjectives that end in -o in the masculine form change to -a in the feminine:

cansado / cansada, aburrido / aburrida, tímido / tímida, etc.

So in this sentence, tímida implies the speaker is female.

Is the comma after tímida necessary? How does punctuation work with aunque here?

Yes, that comma is normal and recommended.

Rule of thumb in Spanish:

If a subordinate clause (like the one started by aunque) comes first, you usually put a comma before the main clause:
- Aunque parezco tímida, mi carácter es fuerte…
If the main clause comes first, you often omit the comma:
- Mi carácter es fuerte cuando algo me parece injusto.

So the comma after tímida follows standard Spanish punctuation for an initial concessive clause.

What is the difference between parecer and parecerse? Why not me parezco tímida?

parecer = to seem / to appear (how something looks/feels to someone)
- Parezco tímida. = I seem shy.
parecerse a = to look like / to resemble (someone or something)
- Me parezco a mi madre. = I look like my mother.

Me parezco tímida would be incorrect here, because parecerse needs “a + someone/something”:

Me parezco a ella.
But to say I seem shy, you must use parecer without se:
Parezco tímida.