Sorry, I apparently picked a bad example with the purring. However, cat-like or feline-like behavior should be considered IC and at least when tempered with a bit of sanity and reason, should be considered good RP as well. Enki's obviously don't walk around on four legs, they have some of the qualities of a more human race (marriage, commerce, property, modesty, etc). But that doesn't mean they can't still be more agile, "always land on their feet", purr, and other things from the more feline aspects of their race.
[EDITed for clarification and typos]