He probably needs to be with another active cat. I hope he finds a good home. Has your friend contacted the breeder who sold them the cat? All reputable breeders will either take back a cat if the owners can no longer keep it, or help in finding a new home if that's not possible. In fact, many stipulate in the contract of sale that the owners must contact them if no longer able to care for the cat. I assume there's an ocicat rescue? Or a breed rescue that includes ocicats. It's important that he's rehomed to someone who understands the ocicat temperament to minimise the chances of him needing to be rehomed again due to someone taking him on without fully understanding his needs.