I am doing my 3rd playthrough and going for the 3 fingers ending (in case that matters to this setup).

On my first playthrough I tried for every possible optional boss, missed a few, but got Placidusax. On my 2nd pkaythrough I skipped him, but on my 3rd, this is where the bug may have happened:

I did Milicent's quest (my son helped me with almost every boss fight, except for Milicent invasion, to play the game together), and after killing Melania, Fire Giant and then Godskin duo, and getting Miquela's needle after Milenia, I opened my map and saw Dragonlord Placidusax grace active. I teleported to it, and skipped the cinematic and he spawned on my head. I died about 8 times before I got him down, changing gear around while he beat me around a bit, but every death restarted in the middle of his room with him appearing directly on top of me.

I'm not sure if this is part of the needle quest, or a weird bug, but I thought I'd ask if anybody here ever experienced anything like this.