Tom is a completely lovable character and that is why the reader will find himself/herself rooting so strongly for his rags to riches story. Tom Canty is the pauper that the book's title refers to. He is a poor kid growing up in the London slums. He survives by begging, and that should tell readers an important piece of information about his personality. He's humble. He's not too proud to beg. He's also brave, since begging at the time was illegal. His home life is pretty miserable too.
When he came home empty-handed at night, he knew his father would curse him and thrash him first, and that when he was done the awful grandmother would do it all over again and improve on it; and that away in the night his starving mother would slip to him stealthily with any miserable scrap or crust she had been able to save for him by going hungry herself, notwithstanding she was often caught in that sort of treason and soundly beaten for it by her husband.
Knowing all of these details about Tom is important because it makes his dreams of being wealthy, or even being a prince, realistic. If he was from a wealthy family, readers wouldn't be so sympathetic to Tom wanting a lot more out of life. He's a dreamer, and he dreams to escape the misery that is his life. Once Tom is given his dream life, readers get to see a lot more of his goodness. Tom could easily become like Edward and be a complete jerk; however, Tom uses his princely powers for mercy and goodness. He altruistically wants what is good for the many instead of what is good for him. He is truly a selfless character.