Right, I have no idea where the inspiration for this came from... but here it is... enjoy? (This is my first Hawaii Five-0 fanfiction)

"No," Danny said down the phone as he got out of his car. "I don't care how much you want to see me, you are not coming to Hawaii – I don't care if you want me to meet your new partner – no – I said no already – Gracie misses you too, but that is not a reason for you to come to Hawaii," By now he was walking into HQ and he was still on the phone. "Dad, I said no. - What's not to get? What can you not understand from that? It's 2 letters – N-o Dad. No," Steve was looking at him strangely now. "Wherever you go Dad – No, don't even argue with that, it is wherever you go – What do you mean 'Is it'? Of course it is! You're worse than Steve!" Chin and Kono stared at him with wide eyes. "I said no Dad, you are not coming to Hawaii! How much is this call costing you? – You're calling from Cardiff, how is this not costing anything? – Right, outside the government - You aren't distracting me, Dad, you aren't coming to Hawaii. – Yeah, whatever, Hwyl." And with that Danny hung up the phone and turned to his team. "What?" He said, seeing that they were all looking at him.

"Danny, why are you not letting your Dad come here?" Steve asked.

"Let's just say," Danny said, splaying his hands out in front of him. "Trouble follows him."

"Didn't you get pissed at Rachel for saying the same thing about you?" Steve asked.

"Brah, you're not letting your Dad see his granddaughter," Chin said. "That's cold."

"If you knew my Dad, you'd get it," Danny said. "Can we please just get to work now?"

"Right," Steve said, before briefing the team on their current case.

Later on, Kono and Chin were out in the field and, as often happens, they got talking. "So, why do you think Danny's so against his Dad coming here?"

"Maybe Danny's telling the truth about him, cuz," Chin said.

"You think so?" Kono asked and Chin nodded. "Maybe you're right." After a brief pause, she spoke again. "What was that that he said, you know before he hung up?"

"I think it was Hwyl,"Chin said.

"Hwyl?" Kono questioned. "What does that mean?"

"Goodbye?" Chin suggested. Kono shrugged. "What language was it?"

"I honestly don't know," Kono said. "I didn't recognise it."

Across the island, Danny and Steve were also talking. "What's so bad about your Dad?"

"I told you."

"What 'trouble follows him'?" Steve asked. "That's it?"

"Yes," Danny said. "Are we really having this conversation?"

"There's got to be a better reason than that," Steve said.

"How about he's an immortal alien hunter from the future?" Danny suggested. "Maybe he's an omnisexual flirt-a-holic? Maybe because trouble actually does follow him!?"

"Okay," Steve said, not catching that Danny was telling the truth. "I get it. You don't want to talk about your Dad. No need to make up impossible explanations." Danny rolled his eyes, but didn't say anything.

Later that day Danny got a call. "Detective Danny Williams?" He said upon answering. "Dad? – What do you mean you're on a plane? – I know what it means! I meant why are you on a plane?" Whatever the answer was had Danny rubbing at his temples. "I told you not to come. I remember explicitly saying no. – Dad, why are you coming here? – I know why you're coming here! Why did you ignore me!? – You miss me?" There was a long pause, in which Steve watched Danny very carefully. Danny's face softened as he listened. "How long till you get here then?" Danny asked, sounding defeated. "Alright, I'll pick you up at the airport. Say Hi to Ianto for me. Yeah, Hwyl i ti Dad." Again, when Danny hung up he found the whole team staring at him. "What?"

"So your Dad is coming to Hawaii then?" Steve asked.

"Yes," Danny said, with a sigh.

"What's so bad about him?" Steve said. "No don't tell me, immortal alien hunter, right?"

"Yes," Danny said.

"Danny?" Kono asked. "What language was that?"

"What?" Danny responded, not quite sure what she was talking about.

"The Hwiltea or whatever," Kono said. "What you said instead of good bye."

"Hwyl i ti?" Danny asked, Kono nodded. "It's Welsh, means fun to you."

"You speak Welsh?" Steve asked.

"Only the odd word," Danny said. "I was born in New Jersey but spent a lot of my childhood in Wales, I picked up a few words."

"If it means 'fun to you'," Chin asked. "Why is it used as goodbye?"

"I don't know," Danny said, throwing his hands up. "It just is."

When Danny went to pick his Dad and his Dad's partner up at the airport, Steve came with him. So did Grace. "Gracie," Danny said. "You ready to see Uncle Jack?" Before they had arrived, Danny had dragged Steve off to the side and explained that Grace thought Jack was her Uncle not her grandfather because they didn't know how to explain it to her.

"Explain what?" Steve had asked.

"His immortality," Was Danny's reply. Steve thought he was joking.

"Yeah Danno," Grace said.

"What about his new partner?"

"From what you said," Grace said. "He seems pretty cool. Is he my Uncle too?"

"Maybe one day Gracie," Danny said.

At that moment people started exiting the gate and Danny kept a look out for his Dad, he grabbed Steve's hand when he saw the RAF coat flapping about in the crowds. "You see him?" Steve asked.

"Yeah," Danny said.

"Danny!" An almost American accent (The accent wasn't American in the first place, but Boeshane) called. Steve thought it sounded a bit off, maybe he travelled a bit.

"Hey Jack," Danny acknowledged his father.

"Uncle Jack!" Grace exclaimed as she threw herself at her grandfather.

"Hey there Gracie," Jack said picking the girl up. "This is Ianto," He said gesturing to the man in jeans and a jacket next to him.

"Hello Ian-to," Grace said, sounding out Ianto's name carefully.

Ianto smiled. "Shwmai," He said. "You must be Grace." Steve recognised the accent as Welsh.

"Yep," Grace said grinning. "Danno, where are Uncle Jack and Ianto going to live?"

Before Danny could think of anything, Steve said; "I've got a couple of spare rooms."

Danny turned to his partner. "You'd do that?"

"We won't be needing a er couple of rooms," Ianto interrupted.

"That's fine, Grace uses the other one," Steve said. Jack looked to the girl in his arms.

"Is that right, Monkey?" Jack asked, using his sons name for his granddaughter.

"Yep, Uncle Steve is great," Grace said patting Jack's shoulders as she spoke. "Can we go now?"

"Just a minute sweet heart," Danny said. "Your Uncle needs to get his luggage."