I still don't own CSI, but Jackson is my original character.

Big thanks again to smuffly, Lil Badger 101, csinycastle85, Tede-Ruxe, McCountryGirl, mirdashian, and all who are reading and reviewing. So glad you all like Jackson so much! Hope you enjoy this chapter!

Jackson loved all his presents almost as much as he enjoyed visiting with everyone who came to his birthday party. He loved just sitting on his Papa Daniel's lap and talking about everything from his presents to butterflies.

"How'd you get so smart?" Daniel asked as his grandson talked about butterflies.

Jackson giggled as Daniel tickled his ribs. "I dunno!"

Greg loved visiting with his extended family, as well as meeting Morgan's mom and stepdad. If asked, he and Jackson both would probably say this was one of the best days of their lives.

Soon, the guests began leaving and said goodbye to Greg and Jackson. Lily and Lindsey both hugged Jackson and told Greg that he had their number if he ever needed another babysitter. Catherine smiled at the young dad, remembering how he'd grown up from being the goofy lab tech to a competent, very good CSI Three.

Greg saw Catherine smiling warmly at him. "What?"

"Just...thinking Jackson's a very lucky boy." Catherine smiled.

Greg looked at the little boy sitting on his grandfather's lap, chatting happily with everyone and smiling. "No...I'm the lucky one."

Catherine walked over and put her arm around Greg. "You both are amazing. You are a good daddy."

"Thanks, Catherine." Greg enveloped his former boss in a hug.

"Do you really have to go?" Morgan asked as Lindsey and Lily got their jackets.

"Oh, yes. Lindsey wants to go see her friends while she's in town," Lily explained. "But we just had to see Greg and meet Jackson."

Morgan smiled as Catherine and Greg walked over to them. "Well, I'm really so glad you all came," Greg told them. "Thanks for helping him have a great birthday."

Catherine hugged Morgan. "I wish I didn't have to go back, but there's a ton of paperwork to catch up on. Plus I want to spend time just with Lindsey and mom."

"We understand," Greg said.

Jackson climbed down from Daniel's lap and rushed over to Greg and the women. "You goin'?"

Catherine smiled as she saw Jackson look up at her with brown eyes that were just like his father's. "I have to, sweetie. But I'm going to talk to you again soon...and maybe we can have lunch together before I have to leave in a couple of days."

"Yeah!" Jackson said.

Catherine laughed. Hugging Greg again, she said, "Thanks again for letting me come meet this sweet boy."

"Thanks again for coming." He and Jackson waved as they left.

Eli and Kaitlyn had a wonderful time with Jackson. Eli especially enjoyed playing trains with his two new friends. "Mommy, can we come see Jackson and Katie again soon?" he asked Tina.

"Maybe so," Tina said. As much as she hadn't spent much time with Warrick's extended family at the lab, she had to admit she enjoyed the company and seeing Eli have such a good time. She thanked Greg for inviting them and left her number with him and D.B. in case they wanted to get the kids together again soon.

Nick, Sara, Doc and Judy all offered to stay and help clean up. That gave Gil a chance to talk to Jackson some more. "So, you like baseball?" he asked the sweet little boy.

"Uh-huh," Jackson said. "I like to, um...my daddy an' me like to play catch."

Grissom smiled. "That's really good. I used to play catch with my dad."

"Did your dad 'splore too?" Jackson asked.

"Well, kind of. He was a botany teacher."

Jackson thought for a moment. "What's bot-an-ny?"

"That means plants. He liked to study plants."

"Oh, cool," Jackson said to a smiling Grissom. "Did he like to study bugs, too?"

Smiling thoughtfully, Gil said, "I think he liked them. He wanted to see how plants and bugs worked together, and he knew I liked studying bugs."

Jackson looked up at his Uncle Gil. "Is he not here anymore?"

Gil shook his head. "No, he died when I was not much bigger than you."

"So you keep him in your heart?" Jackson asked. "Dat's what daddy an' Uncle Nick said dey do with my Uncle Warrick."

Gil smiled warmly at the sweet little boy. "Yes, I keep him and your Uncle Warrick in my heart."

Jackson nodded. "Daddy an' Uncle Nick said Uncle Warrick would like me. Do you think he'd like me?"

Gil smiled wider. "I know he'd love you."

Jackson smiled his biggest smile.

Greg watched his mentor and son, smiling at the sight of Gil Grissom with a four-year-old. He listened to them talk about studying bugs and playing baseball, wanting to hold on to the moment forever.

Sara and Nick emerged from the kitchen and saw Greg watching the two of them. Jackson chatted away about how he liked to play with his father and Morgan, and Grissom listened about how he wanted to go see the butterflies and explore.

"My, you are a very smart guy," Nick said as he walked over to the door.

Jackson jumped off the couch and rushed into Nick's arms. "Are you goin' too?"

"Yeah, I gotta head home and check on Sam. But we'll get together this weekend and maybe play a little baseball."

Jackson nodded and threw his arms around Nick's neck. "I love you!"

Nick laughed softly. "I love you, too. Happy birthday!" He set Jackson down, said goodbye to everyone and left.

"Who's Sam?" Grissom asked.

"Uncle Nick's doggie," Jackson said as he climbed on the couch between Gil and Sara.

"Yeah," Sara said. "Nick has a German shepherd now."

"He police," Jackson said as he looked through the bug book with Grissom.

"A retired police dog," Greg clarified. "Sam's owner was killed, and he helped solve the case."

"Aunt Sara, do Sam an' Hank play together?" Jackson asked.

"You know, I think we should set up a doggy play date," Sara said as she smiled at Jackson.

"Yeah!" Jackson agreed. "We can go to da park!"

Greg laughed softly. "And you can play with Sam and Hank, right?"

"Yeah!" Jackson said.

Grissom laughed softly. "You know, when your Aunt Sara comes to visit me wherever I am, she might need someone to look in on Hank."

"Yeah," Sara said. "And we already know Hank loves you, Jackson."

"And I have a spare key," Greg added. "So next time Aunt Sara goes to visit Grissom, we get to check on Hank."

Jackson smiled widely. "Okay!" He loved visiting with Hank.

D.B. and his family said goodbye and Greg agreed to return to work the following day. Jackson hugged Kaitlyn and agreed that they and Eli should get together just to play together sometime.

Morgan's mother and stepfather left with Ecklie, Olivia and Hodges, leaving Morgan to help clean up and visit with Greg's family.

When Gil and Sara got up to leave, Jackson rushed over and wrapped his arms around Gil's legs. Sara smiled warmly when Gil lifted the little boy into his arms.

"Are you gunna go 'splore again?" Jackson asked.

Gil smiled at Greg's son. "Yeah, I have to go to Peru. That's in South America."

"Is dat still far away from Vegas?" Jackson asked.

"Yes, it is. But I can still e-mail and Skype, and write lots of letters."

"An' call like Aunt Catrin calls my daddy, right?"

Gil smiled warmly. "Right. And Sara can bring me lots of pictures to show me how big you're getting."

Jackson smiled at his father's mentor. "I wanna go 'splore with you sometime."

"I'd like that," Gil said with a soft laugh. "Maybe one day we'll go exploring together."

"An' see da butterflies!" Jackson said.

Gil smiled. "Yeah, we'll see the butterflies."

Jackson wrapped his arms around Gil's neck. "I love you."

Gil hugged the sweet little boy. "I love you, too. And thank you for letting me and your Aunt Sara come to your party."

Jackson saw Sara smiling at the sight of Gil Grissom holding Greg Sanders' son. "Aunt Sara, are you happy you came to my party too?"

"I am very happy," she said as she wrapped her arms around both of them. "I love you both very much."

"I love you, too, Aunt Sara." Jackson smiled when Sara kissed his cheek.

Greg walked up and smiled at his mentor and best friend with his son. "I am so glad you got to come, Grissom."

Gil smiled at the young man he watched go from goofy lab tech to competent CSI. He really enjoyed the party and meeting Jackson. As much as he thought of himself as a loner, he loved the family at the lab.

"Now remember," Gil told Jackson. "We're going one of these days to see the migration of the monarch butterflies."

Jackson nodded. "Yeah, we gunna see 'em migate!"

All the adults smiled. "And if you ever have any questions about bugs," Gil added. "You're Aunt Sara has my phone number."

TBC...