Oda explains how Marco’s Blue Fire works

D: “Hello for the first time, Oda-sensei. I was thinking, I don’t quite understand how “Phoenix Marco”‘s Zoan fruit of the “legendary beast” kind is different from Ace’s “Meramera” fruit.” P.N. CNY

O: “Yeah… To explain Marco’s ability just a little bit: he’s Zoan, so he does have a body. But since he’s got “the blue fire of revival” – the Phoenix’s ability – wounds will regenerate, so attacks will not damage him (though there’s a limit to the regeneration). In other words, the flames are for regeneration. These blue flames don’t have the characteristics of actual fire – they don’t spread and burn things, and they aren’t hot. They’re completely different from Ace’s flames.”

These blue flames are referred to as the “Blue Flames of Resurrection” (復活の青い炎 Fukkatsu no Aoi Honō?) and “Flame of Restoration” (再生の炎 Saisei no Honō?). In fact it was recently revealed that the healing properties of Marco’s blue flames can also be used to treat other beings, albeit to a more limited extent, allowing Marco to act as an efficient doctor.