The first time she kissed him, Walter was caught completely off guard. Granted it wasn't an actual kiss, but he felt the pressure of her lips on his cheek for days.
It was after he had joined Paige and Ralph at Ralph's school science fair. Walter had caused a slight situation when one of Ralph's judges commented that Ralph's experiment seemed to be lacking thought. He hadn't meant to become so defensive, but he had witnessed Ralph put several hours of "rabbit-hole" work time into the project over the last two weeks and had checked the data himself. Not to mention the fact that he hated the look of shock and disappointment on the young geniuses face. His natural instincts took over and he began picking the judge apart in front of the crowd. After his five minute tirade, which left said judge walking away in a huff, he worried that he may have over stepped, but when he turned to look at Paige he saw her beaming with a smile that literally went from ear to ear. Ralph spent the entire car ride home clutching his first place blue ribbon, and recalling every detail of the argument to Walter and his mother.
As they pulled up to the garage Ralph leapt out of the car darting for the kitchen, eager to tell the rest of the cyclone what had happened. Suddenly, the young genius turned on his heels and ran into Walter, giving him a hug. Walter was shocked at first, since Ralph rarely showed large displays of affection, but he quickly wrapped his arm around Ralph's shoulder's. Just as quickly as he had hugged him, the boy was off running to the kitchen again.
Walter began walking into the garage, smiling to himself, when Paige's voice stopped him. "Hey", her voice was quiet and intimate, and Walter couldn't help but watch the rest of the world disappear around her. Before he even realized it she standing next to him. "Thank you", she whispered, close enough to him now that he could feel the heat of her breath on his skin causing it to prickle. He was having to consciously remind himself to breath, when she lifted herself slightly and pressed a warm, firm kiss to his cheek. As she pulled away he thought he could make out a slight coloring of blush on her own cheeks, but before he had time to properly analyze her body language she was walking away from him toward the kitchen. Walter however couldn't move from where he was. He was in absolute blissful shock!
He wasn't sure how long he stood there, but by the time walked into the kitchen Ralph was at the tail end of his story. Toby of course immediately recognized that something had happened, and gave Walter a knowing smile. Walter ignored the behaviorist as he walked over and stood next to Paige, their arms almost brushing.