It is so adorable.

I love all of them :D <3

I really like that way Jack and Bunny stat out as enemies but by the end are friends. I don't know about anyone else but I can see a very strong big/little brother bone forming between these two.

It has the most depth for me.

Gah, how could you make me choose? x) I chose Jack and his sister because even though they didn't get much screen time together, you could still sense their bond. Jack seemed like a good big brother.

Yeah, I agree with missamitza.C:>

Especially when Jack teases Bunny about his fear of riding North's sleigh, causing Bunny to call Jack "bloody show pony" XD

I think of Tooth and Jack as girlfriend and boyfriend

What can I say? They're adorable. Ironic and sexy: perfect match :3 But I'd like to consider the relationship between Pitch and Sandman too (not an option here, of course -.-), because when Black said "you can't blame me for trying, Sandy" to me it really sounded like there was a huge amount of respect implied, like Pitch looked up to Sandman in some way. After all, they do work in the same field. I'd even imagine Sandy tutoring Pitch.

Jack and Jamie's bond is the strongest.... I just LOVE their hug in the end

Although I love ALL of these friendships, I can't help but think Jack is only friends with Jamie because he is his First Believer. Also, just because Jamie reminds him of his sister (not that it's a bad thing)

also baby tooth and bunny, but i love all :D