You used to be Abnegation. But your whole life, you wanted to be Dauntless.

you're parents wasn't proud of you picking Dauntless, since they had always told you to be where you're family is. But you didn't care. You knew where you belonged.

So you had just jumped out the train. And you had to jump down into a pit, but you couldn't see the bottom. If you didn't have the guts to jump, then you was useless to dauntless.