Despair
One of Adam's most painful memory from his previous life was when his mother died, and he rarely talked about it.
He would never forget about his mother, but as days went by, he managed to move on little by little. It was hard, it was painful, but Adam wanted to at least become someone that his mother wanted him to be, so he studied and got a job, but the only thing he didn't have was a lover.
Adam was not always an honest and direct person, he even act childishly at times, and when he was young, he was very introverted and had few friends, so his mother became his best friend.
It was not like Adam didn't talk at all, it was just that he had trust issues since he was little, so he didn't get along with other people, and because of his character, he was very self-centered and got into fights often. Sometimes he wasn't aware of his surroundings and acted like a moron, so other kids tended to avoid him.