How exactly does lycanthropy work? Does it mix with vampirism?
- Can I become a werepire(vampwolf?), i.e. both vampire and werewolf at the same time.
The official strategy guide says this is not possible. The reason is because werewolves are immune to disease, which means you're protected from vampirism.
What's even more interesting is that—because of this immunity—contracting lycanthropy will cure any vampirism you have.
- Can you infect other NPCs as a werewolf?
- Can I somehow infect a giant and turn it into a humongous werewolf?
- Will infected werewolves attack other NPCs?
You're not given any powers that would let you infect other people, so this would be a no as well.
Although Everyone has told you no, there is actually a incredibly simple way to be both a vampire and a werewolf: Hircine's ring, found in the quest Ill met by moonlight. Finish the quest and you'll get the Hircine's ring, which allows Werewolf transformations without giving you the immunity to all diseases. Become a vampire, put on the ring, and Beast Form should appear in your powers menu (under magic). You select it like a shout and you transform into a werewolf, but you are still a vampire and can drink blood and all that.
Additional info: http://elderscrolls.wikia.com/wiki/Hircine%27s_Ring_(Skyrim)
You can become both a vampire and werewolf, however you cannot drink anyones blood, leading to your character being stuck at level four vampirism. If you don't mind everyone trying to kill you then you should do the following:
Do the companions quest until you have to drink the blood to become a werewolf, then leave the Underforge and get infected with vampirism, return to the underforge and wait three days
If it works the same way as it did for me, after waiting three days you won't instantly change into a vampire, you have about 5-8 seconds, I waited about 3-4 seconds into this, then drank the werewolf blood. As the game loads up the werewolf part you should get a message telling you that you have turned into a vampire, right after which it will load up with you being a werewolf.