collaboration - What exercises will help me write my co-author's character?

I'm working on a novel together with my co-author, K. K's come up with this great character - a sassy were-cat name Garlic. Unfortunately, I'm having a really tough time writing for Garlic - K has a feel for the character that I just don't have yet.

I don't want to leave K doing all the work on Garlic - he's going to be a major presence in the book, and I want to be able to write him at least reasonably well. So I want to practice writing dialogue, behavior, viewpoint description, etc., for this character, until I can do a better job writing him.

I'm looking for good writing exercises that would be appropriate for, well, appropriating K's awesome character. Obviously K can help me out with them. I'd like something more directed than "write random scenes with Garlic; have K tell me what I could have done better."

Edited to Clarify: While I'm familiar with many ways to develop a character independantly, I am most interested in exercises which are unique to the situation of writing collaboratively. In other words, I want to know what new options I have available to practice "getting used" to somebody else's character, which I wouldn't be able to do with something that was entirely my own creation.

Disclosure: This is a hypothetical question for the "Collaboration" topic challenge. In reality I have no co-author, nor am I working on a book involving a were-cat. If you would like to apply for either position, please contact me in the chat room. Use the keywords: "RE: collaboration/lycanthropy".