Honestly, Michelle can be portrayed however you'd like as long as you stay in character and seem really happy go lucky and sometimes a bit sassy.  She doesn't have many lines but a few background noises and extras, so...

She's almost always happy.  Despite looking very cute and innocent she loves to prank people and cause mischief.  She dated Feli for awhile a long time ago, but it didn't really work out, they're still great friends though.