Hello, Michelle and welcome!My name is XXXXX XXXXX it will be my pleasure to assist you and Fatty today.My apologies that you did not receive an earlier answer. Different experts are online at various times and I recently logged in and read your question. Your patience is appreciated!I'm sorry Fatty is experiencing this problem and upsetting the family dynamic. From your description, it sounds like his behavior might be due to redirected aggression. This type of aggression takes place when a cat is stressed, frightened or startled and he takes it out on those closest to him. I believe Fatty's stay at your sister's, away from home, when you had your place fumigated, caused him a lot of stress and he is taking it out on Lee and sometimes, you. Cats are creatures of habit and generally don't take well to change. It causes stress and anxiety.First, since this behavior is uncharacteristic for Fatty, it would be advisable to have him evaluated by his vet, just to make sure there is no underlying medical issues causing his current behavior. If all is well medically (hopefully), then this can be treated as solely a behavioral problem.Get some Feliway plug ins; these are plug in diffusers which emit cat appeasing pheromones, only detectable by cats in the house. It helps reduce stress/anxiety and will be good for Tucker, as well. Also, you can try some over the counter oral calming remedies like Rescue Remedy for Pets and Composure liquid and treats. Here is additional information on all these products, available at your major pet supply stores:
Try not to yell at Fatty or punish him when he growls or hisses or this will add to his anxiety. Try to either ignore him (as long as he's not physically attacking anyone) and/or redirect his interest with an interactive toy like a laser pointer or feather wand. Allow Tucker to play with these with Fatty, too. Also, give cat-healthy treats when he behaves well and acts lovingly towards Lee.
Enriching his environment with some new toys and also a kitty condo or cat tree, if you don't already have one, is also a good idea. He will love these types of toys:
Put all their toys into groups and switch them out every few days, so they feel like they're getting new ones. Also, never leave the cats alone with the feather wand/fishing pole toy, as pieces may be chewed off. Play with them under your supervision and then put away the toy where they can't get to it.
If the situation continues with no improvement, discuss with your vet, a calming prescription medication which will help Fatty. Perhaps just a short term use of this type of medication will help him return to his normal, loving self all the time.One more suggestion, since Fatty had been out of the house; take one of your old t-shirts and pet him and Tucker with it, frequently, plus leave it in his bed or favorite sleeping place so he always has your familiar scent near and on his fur, as this should calm him.I hope things improve with Fatty soon and please let me know if you need any additional information by clicking 'Reply' before rating. If you found my answer helpful, a Positive Rating and Positive feedback on the survey, would be greatly appreciated. Thanks! If you would like to request me to answer any new, future questions, please begin your post with "For Cher Only" and I will respond as soon as possible.