The flames bring Harry to his knees. He’s losing composure fast.
“Draco,” he gets out. Through his rising panic, he tries another aguamenti. It’s fruitless, of course. A fiery tiger snaps at his wand hand. Harry has a horrible realization that he hasn’t been in such danger in a long time. Very few wizards can cast the countercurse to fiendfyre, and Harry isn’t one of them, doesn’t even know the spell. It’s notoriously difficult to pull off.
And then, Draco’s there. He’d run through the fire. Even through burning eyes, Harry can see the other man’s violent trembling. Draco has a grave fear of fiendfyre, but he’s solid and on fire and coughing and right there. Harry tries to stand but can’t quite manage it, tries to breathe but can’t quite manage it. And then, there’s strong arms hauling him to his feet, and Harry’s taken back to five years ago when their roles were reversed. Draco looks no less scared, maybe even more so, and so very young. Still, there’s a determined set in his eyes and his grip on Harry is strong. Being dragged is excruciating and Harry can’t help but scream. His legs can’t seem to find any purchase on the ground. After what feels like an eternity, they’re out of the worst of it and Harry can breathe again. Finally, they fall onto the ash covered ground. Harry’s head hits Draco’s palm instead of the floor. When he looks up briefly, he sees the awkward position of Draco’s outstretched arm and knows it was purposeful.
Draco douses Harry with an aguamenti, gasping out the spell, before doing the same on himself. Both of them pant and hack for several minutes. Draco’s still coughing, but Harry can hear him crawling closer.
“You,” Harry tries to say. You saved me. You ran into a fire for me. You know one of the most difficult countercurses to cast. He’s ravaged by a series of coughs and Draco shushes him.
“Of course,” Draco says. Later, Harry would wonder what exactly he meant. Of course I knew the countercurse. Of course- you’re welcome. Of course I’d run into a fire for you.
When Harry catches his breath, he says, “Of course you knew the countercurse. You shouldn’t have jumped in, the flames would have died down on their own.” Draco gives him a sideways glance, and Harry laughs. There’s a pause, and Harry stops laughing.
“I didn’t know I was successful until after I ran in. I thought I could have failed,” Draco says quietly. After a beat. “If I waited, your hair could have been burnt off. Not that it would look any different.” Harry gives him a small smile. He didn’t know if the countercurse had worked but he still ran in.
“I’m glad you’re my auror partner,” Harry shivers. They could have easily both died. Without Draco, Harry would certainly be dead. Harry would bet his life that nobody else in the entire office knew the spell. Even Dumbledore had been reluctant to use fiendfyre: it was just so difficult to control.
“Damn straight,” Draco says, reaching out an ash-covered hand to help him up. Their uniforms are singed, and they have light burns. They’ll most likely need light healing. Still, it could have been much worse.
Draco’s notes:
Countercurse to fiendfyre: the trick: Caster must be willing to give themselves up to the fire in order to truly tame it. The issue is not many people are willing to sacrifice themselves while performing the countercurse, it takes a rare person to do this indeed. However, once the countercurse is achieved once, the ability to successfully cast it is mastered.