I think it would be a good idea to keep the cat away from my seven year old sister since she happens to have asthma.
Will keeping the cat away be something that helps?
The cat could bring in a lot of allergens that could harm my sister.
If she responds bad to the cat it's normal to want to keep it away. It will help her breath better and will make her happier.
What about my wants? I want to see the cat.
Well it is fine that you want to see the cat, you will just have to do it away from your sister so she is ok. It is a great idea to protect your younger sister because it would be sad to see her have to suffer with her asthma.