This word is put to several uses by the people of Delhi.
“Hain?” - sharp, to the point, almost like a jab, with both eyes wide open, eyeballs about to pop out.
“Hainnn?” - with eyebrows arched, maxillary central incisors all visible, representing their dislike for what they’ve just heard.
“Haaaiiinnn?” - Long-drawn out, representing their unwillingness to try and understand what you’re saying. Commonly used by babus with paunches at government offices, especially after lunch hour.