Mukuro held a… tense relationship with his son.
Sure, he was guardian of the mist, leader of his own small gang of misfits, and the most powerful illusionist in the world, but that didn't impress his little boy. It showed in his large cobalt blue eyes every time he looked up at Mukuro that, not only was he disinterested, he really didn't like him.
The reason for that was simple: Mukuro kept trying to possess his mom. It wasn't new news; but to his son, it was kind of like a slap in the face.
After all, imagine having a parents' day at school: 'Well, my daddy wants to take over my mommy's body so he can take over the mafia and then destroy it and my mommy's guardians have to keep kicking his ass to make sure he doesn't. Mommy has sex with him anyway.' Yeah, it wasn't that great.
To little Tatsuhiro, Mukuro was a monster from the fables the Vongola family read to him at night.
Mukuro, nonetheless, tried to salvage the situation.
He sat Tatsuhiro down one day, ruffling his wild, spiky head of bronze hair and stared right into his large cobalt blue eyes with all the honesty he held (which wasn't that much, but he was at least making the effort) and asked: "What do I have to do to make you and I be on better terms?"
Perhaps most children would have said something cute and naïve like a toy or a pet or even something imaginative – "I want you to love mommy and stop trying to hurt her." Unfortunately, Tatsuhiro was not 'most children'; he was a child all of his own breed.
"… I'm sorry, mio figlio, but that isn't possible." He smiled sweetly and spoke down to his son, ignoring his son's intelligence. "You see, daddy needs to take over mommy's body to destroy the mafia."
"… Go away!" Little Tatsuhiro glared up at his father; what with having his father's eyes (or at least one of them, seeing as how Mukuro had heterochromia and he didn't), it was very unnerving. "If you can't love Mom as much as he is meant to be loved, than you don't deserve to even be his lover!" He threw a hand out – purple tentacles rose up and between them. "Go away!"
Mukuro frowned. "mio figlio…" He reached a hand forward and the tentacles – not capable of standing against his superior illusionary powers – fell away. He ruffled Tatsuhiro's hair, much to the annoyed child's despair. "Perhaps I don't deserve to be your mama's lover." He smiled as Tatsuhiro looked up at him, waiting for him to finish that thought; to admit to something finally. "Once I'm done destroying the mafia using your mama~" His hand got slapped away from Tatushiro, the child huffing as he stomped towards the door. "I'll make your mama the happiest man on earth and never ever deny him anything he ever wishes to have."
Tatsuhiro's hand drifted from the doorknob and he hesitantly turned back to his father. "… Promise?" His cobalt blue eyes bore into Mukuro.
Mukuro smiled back at him. "Kufufufufufu…" He waggled a pinkie in the air. "Pinkie-promise."
Step by slow step Tatsuhiro came closer and then hooked his pinkie-finger with his father's. "Pinkie-promise." His expression is completely serious with no childish innocence, naivety, or even a hint of gullible. "Once you destroy the mafia, you have to treat Mom like she's the most precious thing in your world – even more precious than yourself."
"Kufufufufu… of course!" Mukuro hugged his son.
"Mukuro-san."
"Mio figlio, call me papa."
"Mukuro-san, do you care for mom's happiness?"
"Of course!"
"How much?"
"Kufufufufu… do I have to prove this to you as well?" He holds out a pinkie. "I swear to prove care for Tsunayoshi-kun's happiness above all else-…." His smile froze and his pinkie-finger retracted back to his palm. "You don't care for me to destroy the mafia, do you?"
Tatsuhiro smirked. "If you actually do care for Mom's happiness, than you won't destroy the mafia; because if you destroy the mafia, you destroy Mom's family. And if you destroy Mom's family, you will make him very unhappy." He smiled sweetly, a perfect mimic of Mukuro's earlier smile. "So you shouldn't destroy the mafia if you actually love Mom."
"Oya? Who said that I loved him?"
"Are you saying that you're willing to lay the world at his feet but you don't love Mom?"
"… Smart kid." He lifted his hands in surrender. "Fine, I love him." He rested his hands on Tatsuhiro's shoulders. "But I still plan on destroying the mafia." He grinned. "But once I am done destroying the mafia, I shall make him forget everything about the mafia." He butted their foreheads affectionately. "Except you, Darling Chrome, Ken, Chikusa, and I. Does that sound better to you? Better than having to share your mama with all of these people? Don't forget, the mafia your mama holds so dear is also the same mafia devising ways to murder him."
Silence descended – Mukuro let what he had said set in and Tatsuhiro let himself think about it.
Several hours later, Tatsuhiro was lounging in his mom's lap, listening to a fable of a beautiful woman who had been cursed to sleep a hundred years until true love's kiss awoke her.
"Mom, you should let Mukuro-san use your body to destroy the mafia."
"And he fought his way through the- wait, what?" Tsuna stared down at his son with shock and despair. "You've been talking with your father again, haven't you?"
"He made sense this time."
"Tats-kun, please tell your father that, for the last time, I will not allow him to take over my body for any amount of time to do anything."
"He made sense this time."
"He has the strange habit of doing so when he really shouldn't." He kissed Tatsuhiro's forehead, sliding the book onto the nightstand. "We'll finish the story tomorrow, okay? Goodnight, Tats-kun." He nuzzles their cheeks together. "I love you." He shifted Tatsuhiro to the bed and turned off the light on his way out.
"Mom." Tsuna paused at the door, looking back curiously. "Could you sleep with me tonight?"
Tsuna smiled gently, lovingly, and came back to the bed; he curled around Tatsuhiro. "Fine. But only tonight, okay?" He rubbed Tatsuhiro's bronze head with his chin. "Good night, Tats-kun. I love you."
Tatsuhiro's hand slipped beneath his pillow, grasping around the handle of a trident. "I love you too, Mom." He looked up at his mom, studying his dozed expression, his shut eyes and softly parted lips.
He smiled, amusement entering one cobalt blue eye; the other was blood red. 'I love you as well, Tsunayoshi-kun.'
Author's Note: How was Tsuna able to give birth? The answer is easy: it was Mukuro's doing. And, yes, Mukuro possessed his own son to get to Tsuna, but he wasn't lying to his son beforehand.
Mio Figlio – My son (Italian)
Tatsuhiro – great power (Japanese name)