Kishijoten by JCHatten
http://www.tthfanfic.org/wholestory.php?no=21147#chapter1
Only Xander would be selected as an Avatar of Luck by Kishijoten who accidentally forgets to tell him he is her Avatar. Instead of being possessed by a Hyena he is possessed by a leopard spirit. That was the bad luck the good luck was that there was a shaman visiting that was able to incorporate the being in to Xander and made him stronger, faster and able to fight of possession. In trying to escape a car crash Dawn teleports them to another dimension, the Harry Potter dimension. Suddenly Harry as a were-cat (Dawn) and a budding Shaman/Witch doctor/Ninja Cat (Xander) on his side Voldie and the Deatheators won't know what hit them. Great story nothing is easy and no one is super powerful just different powers. Using the dream plane Xander is able to contact home and finds out that they can never go back. They show up after the ministry trip and agree to help train and protect Harry. There is now a third side to the war with Harry developing his own order one willing to attack to protect the innocent.
