Jiraiya was told he would train a ninja who would change the fate of the world. So once he met Nagato with his Rin'negan. He had special inerest in him because Jiraiya thought he was supposed to be the pupil.
Ya he though Nagato is the Child of prophecy because of the possibility that he is the reincarnation of SO6P (Rinnegan). Ofcourse he took special interest on them^^
Jiraiya was told he would train a ninja who would change the fate of the world. So once he met Nagato with his Rin'negan. He had special inerest in him because Jiraiya thought he was supposed to be the pupil.