We have two one-year-old cats, a female and a male from different litters. Heâ€[emoji]8482[/emoji]s sweet-natured and outgoing; sheâ€[emoji]8482[/emoji]s more nervous by nature but very affectionate when sheâ€[emoji]8482[/emoji]s comfortable. When we first introduced them as 10 week-old kittens, she hissed at him for a few days but then accepted him—and theyâ€[emoji]8482[/emoji]ve been friends. For almost a year there hasnâ€[emoji]8482[/emoji]t been any major misbehavior. Then, recently, sheâ€[emoji]8482[/emoji]s picked up a VERY frustrating behavior. It began after their one-year vet checkup, which was quite traumatic for her (as is any forced contact with strangers). When we got her home, she acted “normal†to us, but hissed at our other cat whenever he got close, sometimes even raising a paw defensively. The bad behavior lasted only about 24 hours that time. Unfortunately, itâ€[emoji]8482[/emoji]s starting to become a habit of hers. Whenever thereâ€[emoji]8482[/emoji]s a stranger around, or sheâ€[emoji]8482[/emoji]s disturbed, she hisses at him. Whether his intentions are playful or just curious or indifferent, sheâ€[emoji]8482[/emoji]ll hiss when heâ€[emoji]8482[/emoji]s close. What can we do? We feel bad for our male kitty and want to teach her not to take out her bad moods on him. We also donâ€[emoji]8482[/emoji]t want to feel like we canâ€[emoji]8482[/emoji]t have people over without disturbing the peace at our home. Any thoughts?