Strange Happenings of 31st October 1981

All baby Harry wants is his parents to come home, but it is the 31st October 1981 and they won't be coming back and in the midst of a temper tantrum Harry's magic explodes. In the Great Hall the first morning of term 1976 a toddler appears at the Gryffindor's table, claiming James as his Father. Who is the toddler and what will follow these strange circumstances?