DS big epic best in fandom recs?

[swear_jar]

So in almost all fandoms, there are the big epic stories that everyone and their dog reads/recs, which are usually the best place to start if you're just falling into the fandom (like sayyyyy Conflicts of Interest for SV, just randomly).

I was wondering if anyone can rec me the big epic stories in the due South fandom? Any pairings are fine with me.