hiiii quin i'm curious your HCs when it comes to Marco's healing powers. sitting here asking myself if they only heal wounds or can they heal infections? obvi he can't heal Pops's implied cancer, but is that a limitation of his powers on others or could he heal himself had he the same condition? 🤔
✨Okay so ❤️✨
I have given this entirely too much thought to be completely honest, but I do want to preface it with I think it's completely valid and really fun to have the parameters be whatever you want, or need, for a given story's need.
So, starting with what we know about Marco's proven parameters thus far:
-:- He can heal himself of everything, if memory serves there's even a mention of the fact that he doesn't even feel pain from injuries because of how powerful the flames are for him. -- Haki coated attacks may actually hurt when they land, because haki negates certain aspects of devil fruits. Garp laid him out during Marineford, and Borsalino hurt Marco when he had sea stone on him. Garp's haki is incredible, so it might take someone who is stronger in it than Marco before it would be an issue.
-:- There's a limit to his own healing ability that is likely tied to his stamina. -- In Wano we don't see injuries start to pile up on Marco until AFTER he stood toe to with Big Mom, AND after he halted the progression of the virus on like a few hundred (thousand?) people, and AFTER he tanked King and Queen for a while. He's all scuffy and showing signs of slowing after all that, but it'd be safe to assume Marco's stamina reserves - and how efficiently he uses them - are almost as legendary as his devil fruit.
-:- There's a limit to what he can heal on others that is, as far as I can tell, tied to that person's own stamina.
Which means that the healing Marco can do for others can change from person to person. When he heals Tama (the sphinx on Sphinx) he warns them not to go running around.
My assumption is that Marco can control what he heals on someone else - between Wano and Tama - he didn't heal the wounds on the fighters during the war, only having his flames hold back the disease, because he needed to prioritize that, and because he COULD.
So I can see him using his flames as triage for others. Stopping a bad bleed, setting a bone, etc. So that the person's body can recover the rest. In this way he helps people survive things that they either might not have, or that might have run into complications.
I do think he has solid medical knowledge, even if a lot of it is from experience and book reading, rather than a formal education.
Now to finally answer you XD
As for infection, disease, poison -- I feel like if it's something you body could overcome, he can help speed that up. So if you have an infected cut, he can heal that, and stop it from becoming severe.
If you're poisoned and it's something you could survive, he can make the duration of suffering shorter. Food poisoning comes to mind for me, most people survive that, and most people who didn't, didn't because prolonged symptoms and dehydration were what really got them. So Marco could handle that.
Chronic illnesses aren't something he can heal because there's no end to them. He could, feasibly, reduce the size of a tumor with his powers, assuming the patient had stamina to spare, and make it more safely operable, but that would be it in my opinion. He could probably soothe, mitigate, and make symptoms easier to deal with as well, but would still be limited by the patient's stamina reserves.
So, as the disease progressed, there'd be less he could do. T-T
But I do think he's a solid doctor on his own, and I do see him as completely ready and willing to get help from another - Hongo, Chopper would probably come to mind for him first, especially after Wano.
Marco and Law would be like the rock stars of the cancer world in an AU frankly. 🥰😅 Marco could reduce a tumor's size, and Law has it excised with minimal complications.
Oh! And I do think if Marco had a chronic/untreatable illness that the phoenix fruit would effectively obliterate it. Just because of how much stronger it is in healing him than it is in healing others. I don't think the disease would have the chance to take a foothold.
Unless Marco was trapped in seastone for an extended amount of time and the illness had ample time to take root. But even then I think he'd still end up overcoming it, just because of how canonically insane those regenerative powers of his are. At least in my take on it =3
I mean, if we wanna play it up for the Angst, we can play it up for the angst /nod nod/ (Like the idea of him having a degenerative eye disease, and post Marineford needing glasses cause his time in seastone was enough for the disease to progress a little before his flames could halt it again.)
