I have two cats from the same litter that I adopted when they were around 12 weeks old. They are going to be a year old in two days, and as of recently I have been wondering if there's something wrong.
Chilli is the bigger and much more approachable one, while Luna is very quiet, petite and usually lets her sister be first in a lot of aspects.
Chilli as of recently started occupying Luna's favorite sleeping spots - ironing board, top of a wardrobe, armchair. This would be seen on various occasions and Luna would rarely sleep or rest in these spots afterwards.
I also caught my cats - from what it looked like - playfighting as any other cats would do, however I noticed that it is mostly Chilli that will 'attack' her first and it is also mostly her that will continue after a few second pauses. Today, I was doing my stuff in the bathroom when all of a sudden Luna meowed, very likely asking me to open the door for her. After a few seconds I opened the door only to find that Chilli was literally sitting on top of her and was licking her face. Luna looked extremely uncomfortable and jumped out of Chilli's grasp in a matter of seconds. On several occasions, Chilli would approach Luna and attempt to clean her, however Luna would usually resort to escape.
Although there are times when even Luna sleeps beside Chilli and cleans her, should I be concerned about how Luna is treated by her sister? Oh and also, I think it's valuable to say that Luna is the cat that rubs against the house members' legs and some other furniture, while Chilli does not do this at all. Lastly, my mother spotted that they rarely eat together when given wet food, and that is something that did not happen before. Chilli becomes uninterested with the food when she sees Luna eating it. Chilli would usually eat after Luna is gone and not in the surroundings.
Overall, is there anything that suggests that my cat is bullying her sister, and if yes, is there anything I can do to approach this problem?