Some years ago I described a friend of Dave's role in a series of escapades with Dave as "co-rogue". This was because "Partner-in-crime" didn't fit as it wasn't clear that any crime had been committed, and "sidekick" or "assistant" put Dave too much into the spotlight, and seemed to impy some planning had gone into the events.
On the other hand, it's hyphenated. Does that count?
Talking of hyphenation, I've been cat-, bird-, fish-, flat-, and, until last Sunday, house-sitting. This has gone relatively well, but blogging has suffered under this immense stress. Some posts are brewing in the back of my mind, but until then, you might want to know about a special language I've come up with for talking to one of the cats, Mog. Essentially, you replace every syllable with "mog". For example, if you wanted to say "Hello Mog. What are you up to?" you'd say:
"Mog-mog Mog! Mog mog mog mog mog?"
I'm still working on how to communicate with the other cat, Meg.