Who is Miro from Children of the Mind and what is their importance?

Of all the characters in Children of the Mind, Miro gets the most stage time. Ender's sister Valentine remarks that he is the most like her brother of anyone she has ever met which is an extraordinary compliment given that Val's life has also spanned 3000 years of real time (vs. her relativistic life of about 50 years) back on Earth and she has visited many planets. When necessary, Miro possesses a sufficient amount of Ender's ruthlessness to enable him to convince Young Val that she needs to die in order to save Jane and the others aboard his starship. He is also compassionate enough, however, to feel bad about it.