To alleviate someone from suffering, Buddhism teaches one to practice mettā karuṇā. But it seems to me that to thinking good about someone and wish them the best, we need to have a better version of the suffered person, so that we can disagree with their current version. If we don't have that image, then we wouldn't say the suffered person is suffered at the beginning. Thus, it seems correct to say that in order to practice metta and karuna, we need to have an attachment?
Since this attachment is necessary, then I think it's fine to have? For example I ask this question, thus I have some attachment to it, and that's fine. I think this is related to the conventional truth and absolute truth.
So is it correct the in order to practice metta and karuna, we need to have an attachment to begin with?
Edit: One can simply say that the better version of that person is just a ideal fabrication of them (because they are not actually like that), or just the good side of them that they always have but not shown yet. In either case, I think it's necessary to assume good faith. Would that assumption be an attachment?