Birthright

Damian and Logan Dragovich aren’t ordinary twin brothers. Damian is a vampire, while Logan is a werewolf, and in 1601 Transylvania, such creatures weren’t immortal—aging was merely slowed.
The brothers find that their father, King Lucian, has been abducted, so they embark on a journey to rescue their beloved patriarch. After they discover that it is the Jackal clan who is to blame, their eyes are opened to a deep secret Lucian has kept from the world—the Fire Opal, which opens the Sacred Spring. The mystical spring water grants immortality to anyone who drinks from it, and the Jackal clan members, who age normally, will use any means necessary to get to it.
With the help of Valen, a wood nymph who protects a haunted forest, the twins seek the gem’s location to open the Sacred Spring. They need the magical water if they are to survive battle against the ruthless Jackal clan.