Learn French: Il n'est pas indifférent, mais il est possible qu'il le devienne. - He is not indifferent, but it is possible that he becomes so.

It is the neuter pronoun replacing the adjective indifférent from the first half of the sentence. With verbs of state like devenir (to become) or être (to be), French uses le to avoid repeating the adjective, similar to saying "becomes so" in English.

If we were talking about a woman, would the pronoun change to la?

No, it stays exactly the same. When a pronoun replaces an adjective or a general concept rather than a specific noun, it is always the invariable neuter le. Even if the sentence started with Elle n'est pas indifférente, the second part would still be qu'elle le devienne.

Why is the verb devienne used instead of the indicative devient?

The phrase il est possible que introduces a level of uncertainty or possibility, which requires the subjunctive mood in the following clause. Therefore, we use devienne, the subjunctive form of devenir for il.

Can I drop the le and just say qu'il devienne, like how we sometimes just drop it in English?