Magwitch, as a young man, is what Joe would have been if Joe had been ruled by his passions and reacted to life instead of taking responsibility for his choices. Magwitch is another father figure for Pip, showing both what happens with bad choices and how you can rise above them. During his rough childhood, he kept reacting to life, getting into ever worsening criminal activities. Yet removed from England and placed in a new environment where he is given the chance to become what he was always capable of, he rises to the occasion. The hidden good has a chance to come out. He remembers the generosity of a small boy, feeling the bond of powerlessness and victimization they both shared as convict and child. He recommits his life, this time a conscious choice, to do good. He works hard, so that Pip can live easy.
His flaw is in wanting to return to see and show off his creation. His generosity is great, but it is not perfect and not done just for Pip's benefit. Magwitch wants revenge on society and uses Pip to do it. He wants to create a wonderful gentleman to show society they were wrong about him. He wants to feel proud of what he created. This is his downfall because to return and glory in this is to risk his life. However, he is a true man and accepts that risk knowingly, never playing the victim. He wants to see Pip, will pay with his life if he has to, and is at peace with that. He loves Pip with a simple heart, and, having had a chance to return to the basic tenderness that was always within him, dies with dignity and peace.