Melody smells 'wrong' probably. Cats rely on their sense of smell to recognise eachother . You often get this reaction after short separations. Especially I think if one has been at the vets or to stud for instance as strong scents can be carried from these places back home and upset the resident cat. Rub the scent glands on the side of their faces and keep alternating to exchange scents, and keep swapping blankets between them too. Some people say rubbing baby powder in them both helps as they both smell the 'same' . They just need a bit of time to settle back.

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