TW: Terrorism, Mentions of Violence, Implied Death, Misinformation, Peer Pressure, Mentions of Incarceration, Emotional Manipulation, Toxic Mindsets.
A.N. - Two Jokers down, however many more to go.
Platonic:
The problem begins with Joker shifting the venue for his crimes to the area of Gotham City in which his friend lives. Local banks that they visited a day prior are robbed, and the chases between Joker and Batman almost always pass through their neighbourhood. As Joker directs the lesser criminals to terrorize other sections of Gotham and preoccupy the GCPD, he exploits the scattered and overworked police force to pull his friend into the middle of his crimes.
Privacy is denied as every step they take outside their home becomes a target for paparazzi, reporters, and detectives. Joker adds fuel to the conspiracy theories strangling his friend's social life by strolling to their door with Harley for impromptu slumber parties, using any sympathy they may have for him and promising not to intrude again. In addition to breaking his promise and returning the next night, this fanning of the invasion is further aggravated by his tendency to chat with them while making demands of Gotham at the same time.
As long as they are on good terms with Joker, his friend is protected from a majority of crimes. Many of the rogues, such as Bane and Two-Face, view them as a member of the crime family, and the average business and person knows better than to get themselves hunted by the infamous underbelly of Gotham City for cutting a paycheck or picking a pocket. If his friend is ignoring him or antagonizing him for his life choices, however, Joker allows them to fall into dangerous situations and refuses to help unless they apologize or sufficiently praise him.
Batman has little faith in the goodness of anyone who associates with Joker, and his initial conclusion paints the clown's friend as just another criminal. Any protests against this notion are deemed to be lies, with the vigilante suspecting coercion only if they are an esteemed member of the community or have known him personally for a long time. Joker actively sabotages their plead for innocence by venting to them about Batman in full view of other people and inviting them to join his latest crime when he knows a superhero or batch of civilians are witnessing it.
Romantic:
For all his many trials in evil, Joker has a unique sense of fairness and abhors a blatant show of disrespect for the few people he thinks are more than just tools for chaos. The clown views his extremist methods as admirable when he goes beyond the limits of the law and the moral constraints of heroes to avenge his partner. Once the cameras start rolling, he dedicates the crime to them on live television. The definition of his vengeance ranges anywhere from trapping the offender in a building rigged to explode to taking the last parachute and abandoning them in an airplane with no pilot.
By the end of the same day, news outlets across the city latch onto the story and dramatize it in the form of asking citizens to give their reaction in polls and interviewing superheroes for insight. The Gotham Gazette floods the public with speculative pieces about the relationship, which Joker reads avidly and considers undeniable evidence of his perceived intimacy with his partner. The links are inconsistent at best and specious at worst, drawing a variety of fantastical correlations between their daily activities and the details of the clown's recent escapades.
Unless his partner has powerful allies in the local government, there is a high probability that this will cost their job. All the fearmongering and news propaganda sink their reputation until the GCPD is threatening to arrest them on suspicion of aiding and abetting a known criminal. Joker comes to them on the day of their termination and offers asylum in his hideout, revelling in their need for shelter and a new livelihood.
If Gordan or Barbara succeeds and his partner lands in Arkham, Joker surrenders just for the sake of claiming the cell beside theirs. The guards and warden are instructed to keep the two of them apart as much as possible and at all costs, but this only encourages Joker to track them in the recreation yard and stimulate prison riots if they are placed in solitary confinement. Once he has an idea for his next crime or his partner expresses discontent with the environment, Joker orchestrates a prison break and spills back into Gotham.