The good news is that Neo's blood & urine tests came back with no issues. No infection, kidney, liver or thyroid problems, negative for feline leukemia.
The vet explained that overall his tests look great. He explained that Neo may be epileptic and a seizure may cause him to behave irrationally.
Medication is available for to prevent seizures but side effects are also a possibility with medication.
He also said that some cats just keep their hostility bottled up and something will provoke them to release the anxiety without warning. He recommended trying Feliway and also suggested lavender as a calming agent. I have some lavender oil but also want to buy some dried lavender flowers to put in sachets around the house.
I was able to get a Feliway diffuser last night. The box indicates that it will take 4 weeks to see behavior changes. I will search around on the forums to read about other users experience with the Feliway product.
I'm excited that we have some alternative solutions to help Neo's behavior. If the attacking worsens then we will need to look more closely at using the seizure medication. Though, last night he seemed very relaxed and was sleeping next to me on his back with his legs sprawled out. He looked really comfy!
Thanks again for all of your thoughts and feedback over the past few days. I really appreciate it. I'm also in touch with Nancy, the animal communicator.