YASID x 2 "Vampire" in space and a space opera

Hello,

I've been thinking recently about the reading teacher who helped
introduce me to good SF when I was in 7th grade, and I was remembering
two books he lent me which I have forgotten authors/titles for. Some
of the details are a little sketchy, but here's what I remember:

The one I remember best was about a guy who was a part of the "real"
species that inspired both vampire and werewolf myths. He was immortal
and had to drink either blood or a modern substitute. When he drank
actual blood, though, he had the power to shapeshift into a wolf. I
believe that the bulk of the action took place in space in the future,
although the character had been alive for a very long time and there
may have been flashbacks.

The one that's so sketchy that there might not be anything anyone can
do to help felt like a real classic space opera swashbuckler. It took
place in a universe where there had been humans on a bunch of planets
and Earth was just another human planet. There were also swordfights.
I'm sure this describes a bunch of books, but it's worth a shot.

Thanks!

Connor