Arin Andrews and Katie Hill look like the perfect teenage American couple in love. They hang out together, see friends and go to the movies, but their love is one in a million - Arin was born a girl and Katie was born a boy. They are both transgender. Arin began life as Emerald, a beauty pageant-winning little girl. The name on Katie's birth certificate was Luke, a boy obsessed with computer games. They met as they were transitioning genders and fell head over heels in love. They've shared their love story online - posting videos charting their relationship, the physical changes they experience and the emotional rollercoaster of what it is to be transgender, from the lows of bullying, abuse and suicide attempts to their joy as they undergo hormone treatments and surgery. Arin and Katie's story has inspired millions who have watched their videos online - they have become the poster boy and poster girl of the young trans community.