As I get older and on my current rewatching of the show, I truly find myself loving Lt. Castillo even more as the show goes on. It's like the meme once said (Childhood is when you idolise Batman, Adulthood is when you understand the Joker). In this case it's childhood is when you idolise Crockett, adulthood is understanding Lt. Castillo.
Chip in your favourite Castillo staredown/moments in the series: