There are several potential motives. It could be a case of jealousy. Maybe the old man had a relationship with someone that the murderer desired. Or it could be a random act of violence by a deranged person. The cataracts might not have been directly related to the motive but could have made the old man seem more vulnerable. It's also possible that the old man was in the wrong place at the wrong time and became a victim of a crime that was not initially targeted at him.
Well, it could be that the murderer was after something specific that the old man had, like a valuable heirloom. Also, if the old man had some information that could incriminate the murderer or someone else, that would be a strong motive for killing him. His cataracts might have made the murderer think he was an easy target as well, someone who couldn't identify them clearly.
There's not enough information here to give a definite story. However, generally, if an old man with cataracts was murdered, it could be due to various reasons. He might have been a witness to something illegal and was silenced. Or in a more complex plot, his cataracts could have been a key factor. For example, the murderer thought he couldn't see clearly and so got careless around him, but the old man actually saw something that led to his death.
Maybe she was abused by him and couldn't take it anymore. Or he was cheating and she snapped.
One possible motive could be power play. The teen girl might be in a position where she feels powerless in other aspects of her life, so she exerts power over the old man in this extreme way. Another could be a form of rebellion against social norms. By making the old man crossdress, she is challenging the traditional gender roles that society has set.
Perhaps the old man in the painting was once wronged in life and his spirit is full of vengeance. When the person who gets killed comes into contact with the painting, the old man's spirit senses an opportunity for revenge, thinking the person might be related to those who wronged him in the past.
It could be for revenge, thinking that the humans he's targeting have wronged him in some extreme way. Or maybe he's been brainwashed into believing that it's necessary for some twisted cause.
One possible motive could be revenge. If she has been wronged or bullied severely, she might feel that killing is the only way to get back at those who have hurt her.
Well, in a fictional and very dark context, it could potentially be about revenge. If a woman has been severely wronged by a man in the story, perhaps in an extreme and misogynistic way, she might be depicted as taking this drastic measure out of extreme anger and a desire to cause the ultimate harm. But this is a very disturbing and unethical concept.
Perhaps they are lonely and seeking new companionship. They might see the man as a fresh addition to their social circle or someone who can bring new energy into their lives.
It could be that the cat was influenced by some external factors. For instance, if there were strange noises or scents at midnight that made the cat feel threatened or agitated. And in its panicked state, it lashed out at the nearest human, which was the man. Also, the cat might have been suffering from some internal pain or illness that made it more aggressive than usual.
One possible motive could be fame. People like to hear about extraordinary things, and having 1000 kids is definitely extraordinary. So, the person involved or the storyteller might be seeking attention.