Poor Mr. Pitts. He gets made fun of for his name before we even really get to know him.
MR. KEATING: Mr.…Pitts? That's an unfortunate name.
Even Mr. Keating can't help himself. Then Pitts is forced to read a poem in front of the whole class:
PITTS: "Gather ye rosebuds while ye may/Old time is still a-flying/and this same flower that smiles today/tomorrow will be dying."
It's a pretty appropriate choice for Pitts, since it emphasizes the whole "carpe diem" motto of the film. Does Pitts ever learn to "gather his rosebuds" and seize the day? He does join the DPS, though he joins a bit reluctantly. He's also seen constructing a secret radio and dancing with Meeks; here, the spirit of the DPS might be infecting him.
But most of the time, he never seems to participate in the spirit of the meetings. He's just there, taking it all in.
In the end, though, Pitts seems to have been truly affected by Mr. Keating's teachings. He stands and salutes his captain with the other boys. Perhaps the mentor, and the DPS, had more of an effect than the viewers see.