Danny could truly and honestly say he loved being a girl dad. Ellie was just the cutest, when they found out she wasn't growing they visited Frostbite.
Consulting with other ghost doctors was needed until they found one from a dimension that was very adept at cloning and tube-born babies.
"She'll grow/age once she has reached the time-age of your dimension that fits her physical age."
Danny and Ellie, for a while, didn't much care for that. Ellie was fine, she travelled a lot, but when Danny turned 26 Ellie called in a panic.
"I'm bleeding! Danny!" A hastily made portal and calming down of the girl Danny was on a mission.
"Okay, you stay here, I'll get you pads. You got your first period Ellie!"
Danny may have overdone it. Pads, chocolate, warming packs, cooling packs, hot chocolate, tea, something salty, something sweet, red meat and some plush of a duck-like thing. He got some flowers Ellie had mentioned liking and then called Jazz once he was back in Ellie's hotel room.
"Well, I guess we know you're aging now Ellie!"
"How about you stay at my house for the week? I'll ask to work from home so if you need anything I'll be there?" Danny offered, Ellie accepted faster than she had left Amity Park once she was free.
Danny flew upstairs, looking at Ellie as she was huddled in a pile of blankets on her bed, holding her duck plush so it was looking out and also watching the tablet with her.
"I want ice cream..." Smiling he ruffled her hair.
Ellie stayed. Danny went back to his office eventually but installed a landline so he could be reached by his little hellion.
He loved that Ellie eventually asked for school, and after looking at their options with Jazz on video call they decided that online school would be the best option for now seeing as her education knowledge was all over the place.
"How about a hobby? You are so used to traveling I don't want you to feel trapped."
Ellie joined a dance studio, it was fun and she could move a lot without it being disruptive. Years seemed to pass as Ellie eventually asked to go to the local school.
Through the dance studio she met Cass. And through Cass Steph.
It took about a month until Danny wasn't surprised to see the three girls when he came home. He was welcomed by a chorused "Welcome home dad." from all three.
"How was your day?" He asked as he started dinner for them. Steph had shared her plans to go to nursing school. Cass was undecided for now but was willing to listen to suggestions. Ellie had shared that she was currently interested in photography and wanted to go to an evening course at Gotham U.
Danny may only have one official daughter, but Cass and Steph had their own rooms in his house. He shared joys and sorrows and bought presents and talked with Crystal about Steph's achievements. Cass dodged the topic of parents the longest, until she eventually invited him to meet her actual father.
So, Danny may have forgotten Cass was Bruce Wayne's adopted daughter. He may also have left the meeting with a new number in his phone and no idea what happened in the last hour.
Cass sat on her spot on the couch, watching a documentary. Steph was busy taking a course for first aid. Ellie was upstairs editing photos she had taken of the bats. Cass liked Ellie, she liked Danny, she liked being part of this family as well.
Bruce was her dad, and she loved him for taking that role. Danny was her dad too, in a bit more normal way, Steph had told her how Danny felt like the dad she had wished her's had stayed as. Before the turn to villainhood.
With Danny it was fine if she kept secrets, if she felt unsure about things. She even had Jazz, an aunt who could feel emotions how Cass read them in someones body.
This house was calm and cozy. No prank wars. No plotting against siblings. Just calm. It was her little save heaven and she didn't want to share it with the boys. So she kept it to herself. She shared Danny with Bruce only so he wouldn't fret and escalate.
Only now she had another problem! Bruce was obviously interested in Danny! And Danny was so nervous he didn't even notice, thankfully. Cass liked the idea at first, but then she would have to share her little haven of calm.
So she may have... interferred a bit and made Danny "lose" Bruce's number. And while Bruce had Danny's number, thanks to stalking on his part, he couldn't just text or call without being called out on how he got that number.
Steph found this situation hilarious. She was also fully onboard with Operation: Keep The Dad!
Ellie cared neither way but let them, Danny was oblivious.
Because Danny was just happy caring for them, sharing their joys, sharing their burdens and being there with no pressure.