User blog comment:TheOriginalVampireKlaus/Lydia may be the reptilian shifter/@comment-50.14.78.16-20120619044331/@comment-5208559-20120623035120

The reason Jackson is fighting off the bite is becaues whatever Lydia is she is immnue to werewol bites. That is why in that video Jackson was looking at in Science class it was talking about if you have this certain kind of virus and you get an animal bite it will help you defect it. So when Jackson stopped her and said "you did this to me i don't know if it is through blood or saliva or what but you always mess up things." Saying that when Jackson and Lydia went out and when they made out her saliva got into him so when Derek gave him the bite that virus inside of him is fighting against it.