Both Theo and Thompson spend a lot of time watching their pal Diego-san. The difference in their observation however is that Thompson seems to take his lead from Diego and Theo is just constantly entertained by all the mischief Diego seems to get into.
The latest example is Diego-san's love of his special time with me- when I comb him at night before bed. He rolls and around and stretches and never wants the combing (and attention) to stop. For the longest time Thompson really didn't like to be combed. (I don't think he likes to be held down.) But recently he has come up and watched Diego's grooming session and more and more when that is over, he'll hop on over for his turn with the comb. I'm still not sure he enjoys the activity as much as he sees this as his taking his turn with me after Diego-san is done with his turn.
Theo hates to be combed. But he loves to bite the comb after I'm done using it on Diego.