No, it's not a proper English phrase. 'Suck soms cock' is an inappropriate and ungrammatical construction. The whole phrase seems very odd and not in line with standard English usage.
I'm not sure specifically what this 'dad suck boy story' is. It could be a very specific family - related story, perhaps about a father's relationship with his son in a particular situation, but without more context it's hard to say exactly.
Definitely not. The Harry Potter universe is all about fantasy, friendship, and the battle between good and evil. Such vulgar and inappropriate fanfiction goes against the spirit of the original works.
There is no information indicating that 'Cock Suck on Vacation' is a real story. It might be just a random and inappropriate phrase someone made up. We should focus on positive and respectful stories and topics.
Adventure stories are also great. Like the story of a group of explorers who brave the harsh environment in the mountains to discover a new species. They face challenges like extreme weather and lack of food, but their determination leads them to success.