Actually, I thought the Night Lords had a special place for the Dark Angels (a really dark dungeon with lots of torture instruments!) after the Lion nearly killed Night Haunter and the DA dealt such devastating blows to their fleets.
Other way 'round. Night Lords don't care much about the Dark Angels anymore, but the Dark Angels have a special spot for the Night Lords as they not only know about the fallen, but troll the Dark Angels by broadcasting information about them on imperial channels.
It was also successor chapter of the Ultras (cousin chapters) who were in on the decimation of the 8th..
The new lore (as of Sir Bowden) states that the Eighth scattered into separate company warbands after Tsagualsa. It was the Ultramarines that came down at them in their new coats of paint. (Freshly divided into chapters, like Murtag said). They have fight the Blood Angels a lot, because several Night Lord captains killed several of their captains at Terra. As for the Dark Angels, it's a bit of a mixed bag. The Thramas crusade in its entirety two year span were mostly the Night Lords toying with the Dark Angels. Then the primarchs came to blows at a parlay, (nearly slaying one another, Curze's was stabbed through the back by one of the Lion's captains while Curze had nearly strangled the Lion). The Dark Angels eventually planned a very sneaky attack and destroyed a third of the Eight Legion's forces, maybe less - it is not clear. The Night Lords struck back, and it is hinted at that they either rendered the Dark Angel's capital ship unusable, or damaged to the point of it being scrap (and needing a new capital ship/flag ship to be built)
