To me, those "big brother" type would fall into category 1: married man, and maybe also category 8: weirdoes.
I may be wrong, but normally if the guy is too eager to help, there ought to be some ulterior motive other than just being a helpful, kind-hearted big brother. Could be that he is trying to find his 'younger' self, or trying to prove that he is still charming enough to get 'sisters', or doing good deeds out of sympathy or charity...... I am not sure.
Thanks for your compliment on my English, actually my writing is too casual, not formal enough, definitely not beautiful English, and there are more capable people around lah. ^_^
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