"The truth is, I gave my heart away a long time ago, all of it, and I never really got it back."
Bilbo/Thorin
Gimli/Legolas
As children Frodo and Sam never gave much thought to the absence of a Missus Baggins, after all accidents happen and sometimes those accidents happen before children do.
So, neither of them asked where Missus Baggins was or if there had been one, because of course there had been a Missus Baggins at some point or another, because every Hobbit got married at one point because Hobbits weren't meant to live their lives alone.
There were also the things that Mister Baggins did, things that Sam's parents said he didn't do before. Like making Cram before Frodo and him went to visit his Mother's family, or the sword that he hid in plain sight, little things that he hadn't had or done before his grand Adventure.
When Frodo first came to live with Mister Baggins, Mister Baggins had looked down at Frodo and said that the Others would love him.
As years passed, Frodo came to think that the Others Uncle Bilbo had talked about were the Dwarves that came and went periodically but he nave bothered or remembered to ask and he wondered if Uncle Bilbo's Missus Baggins had been a female Dwarf that he met on his Adventure. But Frodo had dismissed that thought because everybody knew that there were no female Dwarves, that they were carved from stone fully grown.
It was only after their own Grand Adventure that Frodo found himself questioning everything he had ever thought about the absent Missus Baggins.
Frodo and Sam were sitting in the Gardens at Rivendell, laughing and drinking with what remained of their Fellowship, plus Lady Arwen, Bilbo, and Elrond when Bilbo turned to Legolas and Gilmli, in a moment of coherency, the Ring having affected him much more than they had first thought.
"How is King Thranduil doing?" Bilbo asked.
"Quite well…" Legolas said slowly, confused fro the moment.
"And Gloin?" Bilbo asked Gimli.
"Our halls are as full of gold as ever." Gimli shouted.
Bilbo smiled softly.
"Uncle Bilbo?" Frodo began, "Can you tell us about Missus Baggins?"
The other three Hobbits looked up in interest.
Bilbo's smiled changed from soft to sad, "There was no Missus Baggins." He said.
"But there was!" Sam shouted, "You made Cram because of her and you got Sting too."
Bilbo nodded, " But we were never married and she was a he, not even a Hobbit, a Dwarf that I met and got to know on my Adventure."
"Tell us Mister Baggins." Pippin demanded.
Bilbo smiled and indulged the young Hobbits, telling the story of his Adventure, telling them the romantic bits that he had taken out when they were you to avoid the disapproval of the other adult Hobbits and the 'Eww's from the younger ones.
"And when he died, a piece of me died too, so, I went back to the Shire, never expecting to have a child or a reason to live, because the truth is, I gave my heart away a long time ago, all of it, and I never really got it back." Bilbo whispered as he leaned against Gandalf's side and closed his eyes, falling asleep within moments.
The group watched in silence as Gandalf covered the frail Hobbit with one of the blankets that he had with him.
"So he had a Mister Baggins, not a Missus Baggins." Merry said slowly.
"No, he had a Dwarf, a King." Gimli said quietly.
No one knew what to say after that, so, after a moment's reflection on how Bilbo's life might have been if his King had lived they began to talk about other things, Merry grinning as he shouted that Gimli and Legolas were the next cross-species couple with a Dwarf, the two sputtering but neither denying it.
Right then, well, I got bored and wondered what Frodo might think on Bilbo not having a Wife, so this came about. Hope you enjoyed.