Learn Hardcore Norwegian: Han vil aldri forråde en venn.

Vil is the present-tense form of å ville. In Norwegian, å ville can mean several related things, such as want to, intend to, or will in a future sense.

In this sentence, vil gives a strong sense of will/would never. It is not just describing a repeated habit; it suggests a firm attitude, intention, or character.

Why use vil instead of just Han forråder aldri en venn?

Both are possible, but they are slightly different.

Han forråder aldri en venn = a plain statement of fact or habit
Han vil aldri forråde en venn = stronger, with a modal nuance of intention, refusal, or moral certainty

So vil adds something like he would never or he will never rather than simply he never does.

Why is aldri placed after vil?

Because in a normal Norwegian main clause, adverbs like aldri, ikke, ofte, and alltid usually come after the finite verb.

Here, the finite verb is vil, so the standard order is:

Han vil aldri forråde en venn.

This is a very important Norwegian word-order rule.

Could aldri go before vil?