So about a year ago i moved in with my boyfriend, we brought my cat (Brielle, 7) and his cat (Fritz, 3) to the new apartment. Brielle was a bit scared but didn't respond negatively to Fritz, whereas Fritz was hissing and being a general asshole to Brielle. I think this is where the problems began. Brielle grew to be scared of Fritz, and meanwhile Fritz started to accept and love Brielle. Currently, the dynamic between them is that Fritz loves Brielle and often tries to play with her. Brielle never stopped being afraid of Fritz and views her attempts at playing as vicious attacks. This has lead to severe anxiety in Brielle and she is always on edge. When she hears Fritz coming up to her, Brielle runs at full speed which Fritz interprets as playing, so she runs at her and jumps, causing my cat to freak out and Fritz being oblivious to the anxiety she is causing. Brielle has always had hygiene issues (she doesn't groom much and refuses to clean her bum, I have to bathe her weekly) and because of this increased anxiety it's getting even worse. I just want Brielle to be happy. She's never been playful, she prefers to sleep all day or lounge in the sun, but she's so afraid and it makes me so sad. She will hear Fritz's collar jingle from the other room and tense up. Fritz has never hurt Brielle or anything like that, why has she not realized by now that Fritz poses no threat? They eat together, sleep near each other, heck, sometimes we even get them to play with the same string toy together. What else can we do to make Brielle not so scared? We tried calming collars and calming diffusers, we bought Fritz tons of new toys to keep her attention off Brielle, they share a water bowl. I just don't know what else to do. I want to take Brielle to the vet again, (I have before and they said she was probably fine but it hadnt been so bad back then) and see if I can get her some anxiety pills but until then, is there anything I can do to make her not scared of Fritz?