They walked in the front door, Booth still chuckling over a joke Brennan had tried to tell that was only funny because she'd failed so spectacularly in the telling of it. He tossed his keys to the table in the foyer and stopped when he saw Max sitting on the end of the sofa staring at the stopwatch in his hand.
Brennan passed him, slipping off her jacket as she went by. "Hi, Dad." She leaned over and pressed her cheek against his. "Where are the children?" she asked as she straightened, casting a questioning glance around the quiet room.
"Zach's upstairs sleeping and Chrissy's in the garage," he said off-handedly, his eyes flicking back to the stopwatch.
"Why is she in the garage?" Booth asked, his radar beginning to hum suspiciously.
"She-"
Just then the sound of a door opening combined with running feet and a little girl's high-pitched voice reached their ears. "I did it! Time! Time!" Christine yelled. She came to a crashing stop against her grandfather's knees, ignoring her parents as she angled her head to peer at the watch. "I was faster, right? How much faster was I?"
Above their heads, Booth and Brennan exchanged narrow-eyed glances.
"Four minutes, 22 seconds," Max nodded. "Not bad. You were over five minutes last time."
"Yes!" Christine raised her hand and received a high-five.
"But you should be under two minutes," Max added, laughing when his granddaughter's face fell. He patted her shoulder and kissed her forehead. "Don't worry, slick. Just keep practicing - you'll get there."
"I'm gonna go try again right now!" she exclaimed and turned abruptly.
"Whoa there, kiddo." Reacting quickly, Booth grabbed her before she could run away again. "What are you practicing? What's going on?"
His own eyes stared up at him from a miniature version of Brennan's face. "Max taught me how to open the door without a key! I'm getting really fast, too!" She tugged at his hand. "Come on, Daddy, I'll show you!"
Max grinned broadly, his eyes dancing, when Booth stiffened and his face twisted with the same expression he always wore when Max . . . well, when Max behaved like Max. Aware of his daughter looking up at him, he managed to curve his lips into a tight smile. "I need to talk to grandpa right now, honey," he managed to grit out. "Why don't you go play for a few minutes and . . ."
"Okay, I'll go practice and you can watch me next time!" she chirped and took off.
"No, I don't want you to practice-" He spoke too late to stop her; she disappeared around the corner, long dark hair flying behind her as she ran.
Booth advanced on Max. "You . . . " he began, then stopped, took a deep breath and ran one hand over his face. "You taught my daughter how to pick a lock?" A muscle twitched in his jaw.
Max shrugged. "Just a small one. She's only five."
"You-" Brennan stopped him with a hand on his arm.
"Remember what the doctor said about your blood pressure, Booth."
"He's turning our daughter into a criminal!" Booth's arm shot out as he pointed at Max. "A criminal!"
"Oh please," Max scoffed. "Tempe's not a criminal, is she?" He glanced at Brennan. "Chrissy's much faster than you were at her age, by the way."
"I'm not surprised," Brennan nodded. "Her fingers are very dexterous."
Booth was looking at her in shock. "He taught you . . . You never mentioned . . . You know how to . . "
"Not any longer," she said regretfully. "But I remember those lessons more as exercises in dexterity than anything related to criminal activity." She lifted an eyebrow and stared meaningfully at her father. "I was unaware at the time of my parents' history."
"See?" Max's smile widened. "It's an exercise in dexterity."
"No it's not!" Booth insisted. "And I don't want you teaching-"
"Time! I'm done!" Christine ran back into the room, panting. "How fast was I that time, Max? I was really fast, wasn't I?"
"Aw, honey," Max pulled a sad face. "I forgot to time you. Your dad distracted me."
"Daddy!" Small hands fisted at her waist, Christine glared at Booth. "Now I don't know how fast I was!"
"I'm sorry, honey," Booth began and then shook his head. "No, I'm not sorry. Listen, baby-"
She grabbed his hand again and pulled him with her down the hallway. "Come with me this time so you can watch. Time me, Max!" she ordered over her shoulder as she turned the corner, Booth following helplessly behind her.
"I got 'ya, slick!" Max called out. He set the watch and settled his arm around Brennan's shoulders as she sat down beside him, both of them staring at the timer.
"You know Booth finds this type of behavior infuriating, don't you?" Brennan murmured, watching the numbers change.
"Of course."
.
.
Of course Max knows. That's what makes it fun!