It's even more obvious now than it used to be, there were several places in the path of daggers where Olver was described as a very ugly kid. As if Jordan was trying to stress that. Birgitte has said that Gaidal was born and was now 'an infant or a young boy'. Birgitte said he could now be a young boy. Certainly, she would understand the time system and Tel'Aran'Rhiod. She's gone through this many times. Birgitte said that Gaidal Cain had left Tel'Aran'Rhiod. He is therefore someone in the world. I think it is fairly obvious that if he is in the world, he will play some part in the story. Since three books have now passed since that, I think it very probable that Gaidal's character should have appeared by now. If he is currently a baby, it's very unlikely that he will be able to play any role, and someone has to be Gaidal Cain. Olver is the only one who fits the description, and he has been around Birgitte, and he's ugly.