By many, the custom is that the chosson walks out to escort the kallh to the chuppa (IE nisuin of old, where the kallah was brought into the rishus of the chosson), others dont consider the chuppa the nisuin, but, the later parts of the wedding ceremony including yichud and perhaps the hall where the seuda is taking place.
By trolls the minhag is that the chosson escorts the kallah, as evidenced by shrek.