Questions & Answers about Ég vil að hann verði glaður.
Why is the verb verði in the subjunctive mood here?
The main verb is vilja (to want). When you express a wish, desire, or demand that someone else does something, the verb in the following að clause must be in the subjunctive. Here, the phrase ég vil að triggers the present subjunctive form verði.
The English translation says 'to be happy,' so why use verði (from verða) instead of sé (from vera)?
While vera means 'to be' (a current state), verða means 'to become' or 'will be' (a future state or transition). When wishing for a future emotion or condition for someone, Icelandic naturally uses verða. Saying ég vil að hann sé glaður implies you hope he is currently happy right now, whereas verði glaður means you want him to become happy as a result of something.
Why is the adjective glaður in the nominative case? Doesn't the English translation use the object pronoun 'him'?
In English we say 'want him', but in Icelandic, the að clause is its own complete sentence with its own subject: hann verði glaður (he becomes happy). Inside this clause, hann is the subject in the nominative case. Because verða is a linking verb, the adjective that follows it must also be in the nominative case to agree with the subject. Therefore, we use the nominative, masculine, singular form glaður.
If I changed the main verb to the past tense ('I wanted him to be happy'), how would the subjunctive verb change?