backtagging: Yes! I do a loooot of backtagging, and I will literally thread with you until forever. So as long as you don't mind, I sure as heck don't mind :'D
threadhopping: Yes please! Threadhopping makes for funny exchanges, and I like that.
fourthwalling: You can, although I can't guarantee that Colette will acknowledge it. She'll just be like "wow! there's already stories about us? that's so cool!"
offensive subjects: There isn't anything in particular to watch out for.

hugging this character: Yes please! Hugs are great, and while she's not one to breech personal space without reason, she loves hugs.
kissing this character: Haha, feel free to do so. But she's the kind of girl who has gone for yeeeears without telling her love interest how she feels... She's not going to be the one kissing any time soon.
flirting with this character: Go for it! Romance is so cute, although again... warning for Colette's derp.
fighting with this character: I'm open to it! Although, I'm horrible at writing fighting logs, so maybe planning it out a bit before hand would be good?
injuring this character: Also open to it, just give me a heads up.
killing this character: I'm also open to this in specific situations, but let's talk about it first.
using telepathy/mind reading abilities on this character: Yep! Although she's a bit ditzy, you might just hear "SUNSHINE, LLOYD, HAPPINESS, FRIENDSHIP, FRUIT man I'm useless PUPPIES!"