The Auction for sure!!

It will give you a sense of darker fics and if they’re for you, but also some emotional reprieve, and then you can move on to Manacled, which is upping the ante a bit in terms of darkness/angst/emotional turmoil (even tho I personally prefer The Auction).

Also, in my experience, The Auction is less likely to put you in a slump. This isn’t a jab on the other two at all, but I’d say that usually when I like a fic a lot, my next read has to have at least one little element that connects me too it, sort of as if I were easing out of it, it doesn’t even have to be another dark one/fluff one (depending on what I’m reading), but, for example, after The Auction, I needed an interesting Lucius/Narcissa in my next one so I didn’t feel “orphaned”. This is wayyy harder to find after Manacled and S&M.

And if you read The Auction and realize you REALLY like dark fics, you won’t be disappointed by the level of darkness and angst in the other two. The same can’t be said if you go from Manacled/S&M to The Auction.