Doran is much larger than a normal child because of the experiments done on him in the Biscuits Room. During his time in the Biscuits Room, he wore a light colored sleeveless shirt with matching pants. When Kin'emon gave the Straw Hats and children coats, Doran's coat was light colored, with black buttons, and black fur at the hood and end of the sleeves.
His personality is typical to that of a scared timid child. He seems to like the Straw Hats, as he went with them to get out of the Biscuits Room.
Punk Hazard Arc
He stayed with the other children in Biscuits Room on Punk Hazard until the Straw Hats broke them out. Later, he succumbed to the withdrawal symptoms from NHC10, which he and the other children were fed regularly in candy form. Eventually, Usopp knocked the children all out with sleeping gas, and then the Straw Hats chained the children up for their safety.
Doran was then seen breaking out of the chains and attacking Nami and Usopp due to the side effects of NHC10. He then left with Caesar for the drug.
Doran was later seen attempting to break down the door to the Biscuits Room entrance. He then chased after Mocha in the Biscuits Room. After Mocha left the Biscuits Room, Doran chased after her, along with the other children.
Eventually, Doran and the other children were stopped for a short period by Nami. She used her Milky Ball technique to do this. The children ended up breaking out of it though, and continued to chase after Mocha. After Doran, along with the other children, caught up to Mocha and began to attack her, Mocha ate all the candy. Doran, along with the other children got angry at her, but also wondered why she was hurting. He then watched as she was in pain on the ground, and continued to wonder why she was hurting.
Suddenly, Sanji and the G-5 Marines appeared in the hallway. They tied Doran and the other children up, which prevented them from moving.
After Caesar's defeat, Trafalgar Law used his Ope Ope no Mi powers to remove all of the NHC10 and other harmful substances Caesar implanted in the children, and used the SAD Tanker to send the children home, with the intent on having Vegapunk help them return to their normal sizes.
While traveling with the G-5 Marines, Tashigi informed the children that they will see Dr. Vegapunk in a few days.