Harry Potter and The Order of the Phoenix - Prompt:
When Harry and company go to the DoM and get knocked down into the Time Turners' shelves that has a particular side-effect.
Recently-apointed Healer and partial-time Unspeakable Draco Malfoy, 27 years old, gets sent back to their time, as he was carrying a new prototype of Time Turner.
While not entirely knowledgeable about what's happening around him, Malfoy is completely sure that a group of tiny teens is being attacked and proceeds to shield them and cover their backs - especially once he recognizes his Aunt Bella, whom he stuns before she can do too much damage.
Sirius-lives-AU with a dose of fix-it and Drarry friendship that will, hopefully, steer Harry's life to a happier path and even contribute to a Drarry-romance.
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Draco researches about spell damage from Dark magic. It is his main investigation since he was recruited for the Unspeakables once he graduated from Hogwarts. That was one of the bigger reasons for him to earn his position as Healer, admitedly facilitated by his contacts within the DoM.
When he's carrying that TT is clear to see that the device started functioning on its own, so people from his time know he's innocent.
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On Harry and the DA's front, the newcomer is a welcomed addition, since the man is fighting besides them and his help proves to be very useful in detaining the Death Eaters and keep themselves out of harm's way.
However, once their battle ends, and Voldemort's return is undeniable, when Harry looks upon the unknown man he can't help calling out a surprised "Malfoy?"
"Surprise, Potter" answers the young man. "Who would have thought that these were the anctics you were up to thirteen years ago" the blond man chuckled before sending a respectful nod towards the grown ups from the Order.
"But what has occurred?" blurts out Harry. Looking at the TT's demolished shelves Malfoy ventures an hypothesis. "Patil had asked me to bring here the latest prototype of TT, we were going to test it on this shelves to gauge how much effort would be needed to reccuperate it. I assume that once you knocked it down it interacted with my own TT and since I was holding it I was brought to the time of its destruction instead of rewinding the shelves to before that point. Or something of that kind".