The first time Ramona Blue saw the clown she was coming home from work. He was hiding in the sewers and had been watching her walk his way, intending to prey on her. She dragged her heavy makeup carrier, tripping and dropping an expensive brush into the sewer through the drain. She cursed and looked down to see if she could retrieve it.
Her eyes were met with bright blue ones. The eyes she saw resided on a stark white face seemingly plastered with makeup. It was unmistakably a clown, but not quite human.
Ramona was startled and jumped to her feet as the clown smiled from the sewers. She looked back and the clowns eyes were now a glowing orange. She grabbed her makeup case and sprinted the rest of the way home.
Pennywise picked up the item that had been dropped into his sewer. He sniffed it and wondered why it was so important to the human that she would try to get it out of the sewer.
Something about the human had piqued his interest. Her hair and eyes were both a bright blue and she didn't even seem to fear him, she was just startled. What he smelled on her most was curiosity.
The clown decided that he'd be following this human and learning more about her.