The thing with Amarant is he is a wanted criminal who is sent out to get the pendent from Garnet and Vivi with Lani but he only agreed to go because he heard Zidane was with her. Now the problem I always saw was that, you never really know who Amarant is until you meet him. SE failed to make any notice of his wanted posters early on in the game when you reach Treno, unless you noticed it but even then you never see him till the scene of Brahne, Lani and him.

Now with Rags statement about his quote at the beginning. I don't think he says it in the game, but the represents him. His way of life was fighting, fighting and fighting. "The only dependable thing about the future is uncertainly," which is mainly saying, you don't know what lies ahead, what the future will bring. You are uncertain at what lies ahead. So his life was just, survive until I can't survive anymore. That is what I think.