Though it is probably mostly for self-preservation [[spoiler: since the Ventari threatened him]], Rincewind constantly trying to pull Twoflower to safety and then making sure he’s alright after something dangerous happened is kinda sweet.
The luggage’s loyalty and protectiveness towards Twoflower is always worth a smile.
[[spoiler: “Dr. Rijinswand” (Rincewind’s other dimensional part) believes Zweiblumen (Twoflower’s dimensional part) is sick and he is so panicked that he runs around the plane trying to find help. From what this troper gathered they hadn’t known each other for a few hours and yet he was that concerned about the tourist.]]
Rincewind saving a frog who was paddling desperately against a current[[spoiler: near the rim]] was also sweet.