Learn Portuguese (Portugal): O conflito começou porque ele ignorou o que ela pediu. - The conflict started because he ignored what she asked.

When 'what' means 'the thing that' in the middle of a statement, Portuguese requires o que. If you just used que by itself, it would usually mean 'that' or 'which' as a connecting word. Because he ignored 'the thing that' she asked for, we must use o que.

Could I use aquilo que instead of o que in this sentence?

Yes! O que and aquilo que both mean 'what' or 'the thing that' in this context. O que is much more common in everyday speech, while aquilo que can sound a bit more formal or emphatic. However, ele ignorou aquilo que ela pediu is perfectly correct and means the exact same thing.

Doesn't pediu just mean 'asked'? Where is the word for 'for'?

In English, we say 'what she asked for', but the Portuguese verb pedir already means 'to ask for' or 'to request' all by itself. You don't need to add an extra preposition like por after it.

Why are começou, ignorou, and pediu all in the same past tense?

They are all in the Pretérito Perfeito (simple past) because they describe completed, distinct events in the past. The starting, the ignoring, and the asking are all finished actions with a clear beginning and end, rather than ongoing habits or background descriptions.