Whenever I see 'indigo', for some strange reason, my first reaction is always taking out the 'd', making it 'Inigo'. Then I think of The Princess Bride and Inigo Montoya...:)
A book called 'Indigo Star'. It's from a series of 图书 called the Casson Family 图书 (Saffy's Angel, Indigo Star, Permanent Rose, Caddy Ever After and Forever Rose) 由 Hilary McKay. I read them when I was 11 或者 12 and loved them.