Question: when does castiel first show up in supernatural
[{'answer': 'fourth season', 'provenance': [{'wikipedia_id': '19533905', 'title': 'Castiel (Supernatural)', 'start_paragraph_id': 1, 'start_character': 161, 'end_paragraph_id': 1, 'end_character': 174, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '19533905', 'title': 'Castiel (Supernatural)', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 1045, 'bleu_score': 0.9578741135048311, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 6898850723984983656}, 'section': 'Section::::Abstract.'}]}]