XD okay. We'll say the cloaking device hides the different colored blood. But maybe later on something causes a slight malfunction in the device that woudl cause it to show the different colored blood? Or maybe even flicker his appearance here or there, causing her think shes going crazy(maybe this is after her first time getting scratched or bitten by the zombies, making her think shes hallucinating)?
By the way, sorry if these ideas seem out there. I just got over being sick and so I'm not thinking too clearly right now XD