Yvaine's confession of love to Tristan while he's in mouse form.
"you want to know what the captain really said to me? He told me that my true love was right in front of my eyes...(Yvaine starts to glow) ...and he was right."
The rough-and-tumble crew revealing that they've always known that Captain Shakespeare is 'a bit of a whoopsie'.
Really, any moment with Tristan and Yvaine after they're taken aboard Captain Shakespeare's ship.
When Una and Yvaine are kidnapped by Lamia, and Una holds a sobbing Yvaine and strokes her hair.
There's also the scene earlier, where Una steals Dishwater Sal's caravan and drives it to the Wall, just to save Yvaine from turning into a rock in the human realm (and given that Una was Sal's slave, she must have known she'd get in huge trouble for it). And when Una is freed of Sal, instead of running and escaping, she stands her ground and refuses to let Lamia kidnap Yvaine. It doesn't work out so well, but it still was very kind of her.
Yvaine: What do stars do? They shine.
The ending, when Tristan and Yvaine, having ruled Stormhold for many happy years, light the Babylon candle and return to the stars. Nothing like the ending of the book, but still...awww.
The princes seem to genuinely love their sister Una; which may or may not have to due with the fact that being female she does not have to compete with the siblings' heir race. When the brothers see her for the first time after years of separation ( due to Una being Sal's slave for decades) they are delighted.
Septimus seems very keen on keeping Primus alive - even though he coldly murders at least two siblings, he tells Primus to "stay in his tower" and leave the hunting for the stone to him.
This interaction between Septimus and Tristan.
Septimus: When I am king, you must visit me in Stormhold, where you will sleep on silk and drink the finest wine.
Tristran: My family are sheepfarmers, but if you ever pass our way, we'll give you a bed to sleep in, and woolen clothes, and all the mutton stew you can eat.
Septimus: *Puts his hand on Tristran's shoulder* Thank you.
It becomes heartwarming when you realize that Tristran has offered to share everything his family owns with a near-complete stranger, but that it may also be the first time anyone has given Septimus anything, no strings attached, just because they like him.