Out of all of the characters who do you think was very influential to siddhartha ?

I think Govinda is the most influential. Govinda is Siddhartha's childhood friend. He is a foil to Siddhartha, serving as a benchmark for the latter's progress toward enlightenment. Govinda spends part I of the novel with Siddhartha and then leaves to follow the Buddha. He reappears at points of transition in Siddhartha's life, and is with Siddhartha at the novel's end to learn his wisdom.