Compare the sentences:
After all he has done for me, he needs my help.
After all he has done to me, he needs my help.
The first one implies that the subject has done good things for the speaker and now the speaker has the opportunity to repay him; the second implies that the subject has wronged the speaker in some way(s) and now needs the speaker's help.
Is there any context in which "do for" could carry a negative meaning, or "do to" could be positive?