My betta Watermelon chose me, so I know exactly what you mean
When I got him there were 5 or 6 other male betta's in little containers next to his and they were all red like Watermelon. At first I went for the biggest, brightest fish and was just picking up the container when I saw a pale, almost finless, pathetic for lack of a better word, betta watching me. I put down the other fish and took a peek at the tiny betta. He was bobbing up and down and just staring at me. I knew he was the one.
Needless to say, I took him home and I'm glad I did! He's now a huge, gorgeous, bright betta with long elegant fins <3