» Sun Nov 18, 2012 5:01 pm
Serana loves the dragonborn and his/her blood so she is willing to give you the gift of Vampirism whenever asked..though most of the time if you are a human she tries to tempt you with flirting and such to become a Vampire.
Aela only turns you ONCE more into a werewolf after being initially a werewolf and cured, Aela doesn't get anything out of it unlike Serana who gets your blood and to possibly spend eternity with you.
If you mean Vampire Lord form and Werewolf form.
Vampire Lord you can enter at will and exit at will nonstop.
Werewolf is once per day unless you have the ring of hircine.