User blog comment:Mangetsu20/A Slayer's April Fool's! (FT - 479)/@comment-5675031-20160403162206

My head canon is that Igneel's power was just that a reserve of Igneel's power given to Natsu that increased his power similar to second origin. In order for Natsu to be able to control that power however he had to gain access Dragon King Mode. Explains why he was training for 10 months cause he needed to gain control of Dragon King mode but if it was just single use he couldn't of really trained for it