Mister Negative is not featured in the old Spider-Man comics. The character was introduced later in the franchise's history. The older comics focus on other villains and storylines.
The 'Mr Negative' origin story likely involves the creation and backstory of a character named Mr Negative. It could be from a comic book, movie or some fictional universe. Usually, it would tell how he became the character he is, what events led to his transformation into a 'negative' entity, and what his motives and goals are based on his origin.
It all starts when Peter Parker gets bitten by a radioactive spider. This gives him amazing powers like super strength, the ability to climb walls, and a 'spider sense'.
In the comics, there's no clear indication that Negative Man is gay. His character is mainly defined by his powers and adventures rather than his sexual orientation.