Learn Swedish: Varför är han alltid så ovänlig mot oss? - Why is he always so unfriendly towards us?

The prefix o- is a very common way to negate adjectives in Swedish, working just like 'un-' or 'in-' in English. Here, it attaches to vänlig (friendly) to create ovänlig (unfriendly). It directly builds the negation into the word, so you don't need to use a separate word like inte.

Why is the preposition mot used here for 'towards'? Doesn't it usually mean 'against'?

It does often mean 'against', but in Swedish, mot is the standard preposition used when describing someone's behavior or attitude towards another person. You will see it frequently paired with adjectives of personality and behavior, such as snäll (kind), trevlig (nice), and ovänlig (unfriendly).

Why does the adverb alltid come after är han?

This is a good refresher on the Swedish V2 (verb-second) rule. In a direct question starting with a question word like Varför, the verb (är) must take the second position. The subject (han) immediately follows the verb, and then comes the sentence adverb (alltid).

Does the o- prefix change how the adjective agrees with plural subjects?