For example, what makes 相手になる different from 相手にする. I know that 「～になる」 is to be/become something, and 「～をする」 is to do something, but what does each imply when used?
What's the difference between the constructs [adverb] なる (naru) and [adverb] する (suru)?
(The 相手 in 相手になる is the subject, and the 相手 in 相手にする is the object... as you might know...) Are you asking about 「～"に"する」 or 「～"を"する」？Because the 相手 in 相手にする and 相手をする are not the same person.– user1016Feb 11, 2013 at 0:33
@Chocolate: this is an ill-chosen example I think. The question seems to be about adverbs so I used a different adverb in my answer.– user18597Feb 11, 2013 at 0:33
2Oh.. I think 相手に isn't an adverb but.. is 暖かく an adverb?– user1016Feb 11, 2013 at 0:40
3By "The 相手 in 相手になる is the subject, and the 相手 in 相手にする is the object", I meant to say-- "In 'AがBの相手になる', A becomes the 相手. In 'AがBを相手にする', B becomes the 相手." (And, in 'AがBの相手をする' A becomes the 相手.) Here, になる is like "to become~", and をする is like "to play a role as~" and にする is like "to make~"– user1016Feb 11, 2013 at 0:53
Suru is active and implies somebody does something, but naru is passive and implies something happens. For example:
暖かくする / atatakaku suru = make it warm
暖かくなる / atatakaku naru = get warm.