Help me find this bl

I read it a while ago and only remember the ending. I believe the uke wanted to help the seme get the plans for this crazy weapon (I think) and the semes brother has them and lures the uke with them. Then I don’t remember what happens next and only that the brother had a thing for blood and the seme helped the uke, I believe it had a decent amount of action in it and that it was a yaoi, sry it’s super vague

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