ok here it is its very easy i will do a shoutout to the first 5 people who guesses it

I am a a kin of a medicine cat.

Long ago people looked at me disgust, they didn't see the inside but the outside.

again and again i had to prove, i lost a kin that way.

I go on a journey far away to find midnight.

Again I had to prove, my loyalty by killing my own kin.

thought I was a father but wasn't which tore my heart in half

I proved them wrong you see, I was loyal and kind not like a kin of mine.

I now recognized as noble and great cat.