Shakespeare derived a great deal of inspiration for his plays from the Ancient Greek and Roman classics. He particularly was very inspired by both the Roman comic playwrights Titus Maccius Plautus and Publius Terentius Afer, the later being better known by the name of Terence. From both of these Roman playwrights, he especially derived the idea of using stock characters. Stock characters are simply character types that we see being used repeatedly within a specific literary genre ("Shakespeare's Plays: Comedies"). Shakespeare specifically made use of stock characters in his comedies like the hero's or heroine's parent or guardian, characters who create the obstacles, ill-tempered wives, soldiers who brag, outlaws, clever servants, clowns, fools, and even female characters who other characters confide in ("Shakespeare's Plays: Comedies"). Adam's role is that of a stock character, particularly a helpful servant.
Adam only appears in three scenes; however, a stock character is not necessarily defined by how large or small of a role the character plays. Some stock characters appear in every single act, such as the fool Feste in Twelfth Night. What does define a stock character is what the character does. We first meet Adam in the very first scene, and, in this scene, he is lending Orlando a helpful ear as Orlando complains about his sorrows concerning his brother's treatment. Adam even offers a helpful warning that Oliver is approaching, so Orlando should cease complaining. When Oliver and Orlando break into a physical fight, Adam even helpfully begs them to stop fighting in remembrance of their father who Adam served before serving Oliver. More importantly, in Act 2, Scene 3, Adam dutifully warns Orlando that Oliver is about to torch Orlando's home, hoping to kill Orlando in the act. Out of love and loyalty, Adam even gives Orlando his life's savings for retirement, so that Orlando can have money to escape his brother. What's more, even though Adam is very old, out of love and loyalty he even offers to escape with Orlando as his helpful servant, as we see in Adam's lines:
Here is the gold;
And all this I give you. Let me be your servant:
Though I look old, yet I am strong and lusty ["vigorous"]
Therefore, my age is as a lusty winter,
Frosty, but kindley: let me go with you. (II.iii.45-53)
Adam's willingness to be such a helpful servant, even exceeding the bounds of his role as a servant to rescue Orlando by giving Orlando his life's savings, shows us that Adam's role is as a helpful servant stock character. What's more, Adam is willing to help Orlando because he loves Orlando as well as loved Orlando's late father and, therefore, wants to continue to be loyal to both Orlando and Sir Rowland de Boys's memory. Hence, Adam's role is as a helpful, loyal servant stock character.