I'll echo the sentiment in that thread: SoD is one of the most comfortable fics I've ever read. It's like something warm after a cold day, it's just so relaxing to read. Northumbrian's other fics all mostly aim for that same atmosphere, and she (presumably) is an expert at hitting just the right notes to accomplish that. Furthermore, while everything takes place in the same universe, it never feels like she's hitting you over the head with that fact or requires you to read everything else first to get everything. On the other hand, I feel like when she tries something else she loses something in the transition. I read most of the Muggle Interface Team series and it just doesn't work as well, IMO. It might be because of the heavier reliance on OCs, the fact they mostly revolve around Muggles, or because it sometimes feels like Northumbrian has to pull herself away from writing the more comfy style she's used to, but I feel like those are (while still very readable) more 3/5 to 3.5 material rather than the 4/5s her other fics are.