» Sat Nov 17, 2012 11:50 am
Their eyes change color, but do not glow*, and they are considered a vampire for all things that check for the "vampire" keyword (for example, if you perform Harkon's prophecy, they will be quite pleased at the blotting of the sun).
They do not use Vampiric Drain or reanimation spells, unless they did before, and do not gain the generic vampire resistances or weaknesses.
Your spouse is by default protected, so they may only be killed by you, barring a few errors, like poisoned dart traps.
*Not Bethesda's fault. The glow is attached to the mesh of the eye, not the texture, and the only way to change an NPC's eyes would be to change their race, creating an ugly color mis-match between their face and body.