Early Seasons:
* Introduced as a football player who joins the Glee Club due to a bet.
* Develops a relationship with Quinn Fabray, but it ends due to his desire to have a "real" girlfriend.
* Shows a talent for singing and becomes a valuable member of New Directions.
* Becomes close friends with Finn Hudson and helps him navigate his feelings for Rachel Berry.
* Struggles with his father's gambling addiction and his own self-esteem.
Later Seasons:
* Leaves the Glee Club for a while to pursue a football scholarship, but returns for a brief time.
* Begins dating Brittany Pierce and they develop a supportive and loving relationship.
* Struggles with the loss of his best friend Finn.
* Leaves for a year to attend a school for performing arts and later graduates.
* Returns for the final season to support his friends at their final performance.
In the final season, Sam graduates from the performing arts school and is accepted into the army. He proposes to Brittany, but she breaks up with him after seeing him getting a haircut for the army. He leaves to join the army, but it's unclear if they get back together.
Overall, Sam's character arc is about finding his own path and discovering his passions. He initially relies on athletics and superficial relationships, but eventually finds his place within the Glee club and develops meaningful connections with others. His final departure to the army suggests a desire for a different challenge and a new chapter in his life.