I honestly never suspected that the side quests given by your fellow vampires would be continous like the quests given by the guilds after you finish the main questline. From the way you get the quests it makes you feel like one of those "important" quests and not just another continous side quest. I thought the side questline was actually going to end somewhere at some point but I've already done like...20 quests now I think and I'm still continously getting more quests from my fellow vampires. Very beautifully well done Bethesda!