Bartleby's history is pretty ugly. Zinna created living scarecrows from people she had power over, and the transformation was tied to what she did to their minds. Bartleby was caught up in that history, too. His appearance is a reminder of the damage she had already done to Oz before Dorothy arrived.
When the others encounter him, being associated with the witch has made him a target. Glinda intervenes, and his knowledge of the imprisoned wizard Grafft gives the group a reason to bring him along. He has information they need, even if some of the people around him aren't ready to trust him.
There is also a reason for his fear of fire. He is made of straw. It is a very immediate danger to his body, which makes the pressure put on him over being afraid feel different. He is traveling with people who can survive things he can't afford to shrug off.
His part in the confrontation with Lynessa matters because that fear has already been established. You have seen how frightened he can be, so his actions under threat mean something. A character doesn't have to stop feeling afraid before he can help someone else.
Bartleby also has room for compassion. His conversation with Thorne lets him respond to somebody else's shame without piling more onto it. For someone who is often the nervous member of the group, he can be remarkably generous about another person's weakness.
Bartleby's history is pretty ugly. Zinna created living scarecrows from people she had power over, and the transformation was tied to what she did to their minds. Bartleby was c…
· Comics / Grimm Universe