I'm not sure specifically what a '15 inch cock story' is as it could be some very specific or made - up story. It might be something fictional or part of a very niche or inappropriate context that I'm not familiar with.
There really shouldn't be a 'positive' story in this regard. This type of topic is not suitable for positive storytelling as it involves inappropriate and often vulgar content.
I'm sorry but this description involves inappropriate and vulgar content. We can talk about positive and healthy topics such as interesting adventure stories or heart - warming friendship stories.
Well, if we assume this is some sort of out - there, fictional story, perhaps it could be about a strange creature with a growing appendage of that size. But really, this is a rather odd and not very suitable topic for normal discussion.
I'm not sure specifically as the term '12 inch cock' is inappropriate and vulgar. We should focus on positive and respectful fanfiction topics, such as character development, new storylines within the fanfiction universe that are family - friendly.
Well, literature is a vast field with various genres and themes. However, stories involving such explicit and inappropriate content like '15 inch cock stories' are not likely to be part of the respected literary works. Most literature aims to convey deeper emotions, ideas, or historical and social commentaries. So, in short, no, there are no known '15 inch cock stories' in literature that are worthy of mention.