Greek and Latin are fun! I used to love having someone read out a Greek/Latin derived word in the dictionary and guessing what it meant based on the components. I love how basic they are.

I also get obsessive over certain roots. For a long time I was really fascinated by the "-ject" root. I took a certain delight in parsing the basic meanings of words with that root and trying to figure out how the metaphor got there.

(Also, one time my sister and I were discussing a meeting between a unicorn and a triceratops and I wound up trying to figure out the Greek word for "unicorn" myself. I came up with "monoceros," and later learned that actually was the word, and was inordinately proud of myself.)