Another possible theme could be discovery. They could discover new things about themselves or their abilities while interacting with each other. Maybe Tundra has a hidden talent that Rocky helps bring out, or vice versa. And this discovery could lead to them becoming even better Paw Patrol members and closer friends.
Well, you can try looking on fanfiction.net. There are often a variety of Paw Patrol fanfics there. Just search for 'Rocky x Tundra' and you might find some interesting stories.
The Hunter x Hunter manga is unfortunately not complete. The author has faced various issues that have led to intermittent breaks and an unresolved storyline.
The Hunter x Hunter manga has indeed concluded. However, the ending might have left some fans wanting more or with mixed feelings depending on their expectations.