Cats Not Getting Along?

So I will have had Lyra for two years on June 2015 and since the house is empty because I work a lot and so does my husband and the kids are usually busy I thought it would be a good idea to get another kitty. We did get one in November and now it's almost January and the two don't get along at all.

It's so bad that Giselle (the new one) must be isolated in my room because every time she sees Lyra she full on attacks her or chases her into somewhere she can't get.

Lyra is a loner and doesn't like affection, but will be held for long periods of time and sleeps with me. She also gets along great with dogs quite instantly. Giselle loves affection, she follows anyone anywhere and rubs you until you pet her. They are complete opposites and they are both around the same age. Giselle is only a few months older but drastically bigger maybe even double Lyra's size.

Lyra never starts the fights, but will hold her ground and I just don't know what to do. I don't want to get rid of Giselle, but Lyra is scared out of her mind. I've done all that I've read, the litter box is in my room as well as the food which is always full. I've tried getting them accustom to each other's scent. The only problem is that Lyra has been sleeping in my room since she was 7 weeks old, but I have no other place to put her because when we first got her all she did was hiss so the kids don't want to house her in their room. Please help.

I've tried putting a bell on her so Lyra can hear it and I've tried putting a harness of Giselle so that if she goes after Lyra we can hold her back, but when we put it on she won't move anywhere or she will army crawl a very short distance and after a while jump very high in the air twisting and turning like a fish out of water. Whenever they fight Lyra pees a lot and it makes a huge mess. If this keeps up my only choice will be to give up Giselle.

By Ashley T