Hiccup: "[Your Viking's Name], I'm glad you're here. Mildew used to complain everything back on Berk, and it's no different on Icestorm Island. He's been talking my ear off about dragon dropping on his house.
Could you do me a favor and talk to him? He seems to listen to you more than me."
1- Talk to Mildew
Mildew: "Look at this disgusting mess! I wake up to find that these horrible dragons ruined my roof. Someone needs to rid this island of them for good!"
Hiccup: "Oh, boy... Well, we need to figure out what kind of dragon left these droppings. Fly over Mildew's house and look down on his roof to investigate."
2- Investigate the droppings on his house
Hiccup: "Wait a minute... Those aren't dragon droppings at all. Those are bird droppings.
Do you see any birds nearby? If we can point them out to Mildew, he'll stop blaming dragons. Fly around Mildew's hose until you see a flock of birds."
3- Investigate the source of the droppings
Hiccup: "That explains it! Even though puffins spend most of their lives at sea, they like to build nests in craggy cliffs, like the one next to Mildew's house. They return to land to lay their eggs. They must fly over Mildew's house!
Go back to Mildew and explain to him that breeding season migration pattern are why the puffins are dirtying his house. Hopefully, he'll listen to you."
4- Talk to Mildew
Mildew: "Puffin droppings? Bah! I don't believe you. If birds were responsible, then how come this hasn't happened before? As soon as you dragon-trainers show up, my roof gets soiled. Explain that!"
Hiccup: "They'll come back to the same nest every year, so this will definitely happen again. You see, many bird species migrate seasonally to warmer nesting grounds, just like dragons. The puffin migrates from sea to land, but other birds have longer migrations. The arctic tern even flies from the Arctic all the way south to the Antarctic!
Mildew will have this problem on his hands every year. Let's teach Mildew about bird migrations. Tap on Mildew to explain everything to him."
5- Talk to Mildew
Mildew: "A likely story, but you can't fool me! I know those are dragon droppings and someone better help me clean it off."
Hiccup: "Well, it was worth a try. I guess we'll still give him a hand. I bet Mildew will have a hard time getting hot water to clean his house.
Luckily, we know a place where we can get some hot water! Could you go to the hot springs and fetch some hot water in the geothermal area of the Ice Caves?"
6- Fetch hot water from the hot springs in the Ice Caves
Hiccup: "That;s plenty. Good work!
You've been a huge help, [Your Viking's Name]. Thank you! Bring the hot water back to Mildew. Hopefully this will be settled."
7- Bring the water to Mildew
Mildew: "Making amends, are you? Well, I forgive you. Just keep your dragons off my property!"