Haven't been able to test this yet, but does anyone know if you can order Serana or your vampiric spouse to use the Bloodstone Chalice, and gain it's buff (Kind of like how you can order followers to use shrines)? Serana seems to use the Vampiric Drain spell a bit when she starts to get low on health, so that buff would be awesome for her.

*Bump*
If this does work, it'd be awesome. Vampiric Drain's damage actually scales with Serana i think because she's an NPC, so being able to leech back Stamina and Magicka as well as the Health, would be awesome for her. If the Magicka Absorb is sufficient, she could keep it up indefinately.

Is the blood chalice even useful for our regular character?

If you do the radiant quests and get the various petrified remains of the ancient vampires, then the buffs grow to a certain level, and then start to last for a progressively longer number of days.

So yes, by doing the quests, it becomes very nice.

Yeah, it lasts for up to 5 days fully empowered with the remains of Ancient Vampires if i remember right. I'm just wondering if i can order Seranna to use it, like how you can order followers to use Shrines to recieve their Blessings.

only for VL form.
vampiric drain is still weaker than throwing a sweetroll at someone.