Disclaimer: Katekyo Hitman Reborn belongs to Amano Akira.
They called it schizophrenia.
A disease that wove blood-stained illusions of people and places and things that did not, could not exist into the open net of human consciousness, and caused hallucinations that felt far too real to be safe. He was ill, they told him, with a mocking, malicious disease that gripped his mind and soul like a silk-lined vice, unrelenting but so gentle that he could not bring himself to hate it.
After all, these poisonous, lovely delusions were at once destined to be his salvation and his downfall, as they gave him a chance to get a glimpse, however brief and painful, of those he had lost.
Of those he had not been able to protect, those he had allowed to die and whose blood was imprinted so deeply and completely into the skin of his hands and the crevices of his iron-willed heart (but iron melted is as malleable as liquid, Tsuna-kun, Mukuro had whispered through Chrome's petal-soft lips, as he kissed a burning trail down his neck - and perhaps that is why you suit us all) that he could not forgive or forget their absence.
Today's visit, he soon realized as a familiar lanky form with sea-green eyes and a Casanova smile materialized on his desk, was his first failure, and one of deaths he regretted the most.
"Hello, Tsuna-kun." Lambo drawled, one eye drawn closed in mimicry of a sleepy wink, as Tsuna turned around after snapping his door's lock in place. After far too many close-calls, (like when Yamamoto had caught him once, cross-legged on the floor, murmuring questions over a map studded with pins to Gokudera – who had been long gone by then) it had become a crucial habit.
"Good morning, Lambo-kun." Tsuna smiled, and shuffled rather reluctantly towards his imposing mahogany desk, eyeing the metre-high stacks of paperwork with resignation.
"Paperwork, eh, Vongola-nii? I guess your dream of becoming a simple office worker did come true, at least partially." Lambo mused, moving from the desk to a long leather couch, draping his long, slender limbs over the couch as he stretched across it to sleep.
"Well, wake me when you're done."
Tsuna merely smiled, thinking – it's not too bad today, not like the other times he came - and shuffled through his papers with practised ease, and continued writing and signing and stamping until late afternoon. He always saved the worst papers for last – the casualty papers.
Much to his dismay, the first target was a young hitwoman that looked unerringly like I-pin, and his low sigh of weariness woke Lambo from his slumber. In an instant, Lambo was behind Tsuna, peering curiously down at the paper. Lambo's eyes (or rather, eye) darkened immediately with something that reminded Tsuna ominously of thunderclouds and lightning.
"So you've let another one die, eh, Tsuna? Let another child suffer alone, parentless, only to be gathered into the darkness of the Mafia?" Lambo's voice was hoarse, dark, and his eyes were cast into shadow. "Did she die like I-Pin died, ripped apart by bullets and knives, or did she die like me, tortured and killed, because you did not deign to save her?"
Tsuna looked at Lambo and did not see the proud, brilliant boy he had made his Lightning guardian. Instead, he saw socketless eyes and charred flesh, and as Lambo reached to touch his hair, Tsuna saw blood-stained hands with neat, centimetre-wide holes ripped through them, and was hit by guilt for the millionth time.
Lambo was first, torn apart by a group of Millefiore monsters that had revelled gleefully in their luck at finding such a young and weak member to kill as an example for those who would stand against Byakuran. Separated from Gokudera on a desperate duo mission, he had no chance against the cruel and experienced veterans Byakuran had raised ("Tsuna, come quickly, please, I don't think I can hold them off for long, Lambo choked out, his puberty-deepened voice cracking in panic, I can'-). They had created a device to neutralize the lightning that had been Lambo's greatest strength, and returned the electricity a hundredfold, until even Lambo had not been able to bear the strength and had writhed in agony for days, until they killed him in a final act of jeering mercy. They had gorged out those pretty viridian eyes and nailed him to a replica of the Vongola crest, hands nailed through with lightning rods and one eye stitched open in a mockery of his living face.
"I'm sorry, Lambo." Tsuna whispered, honey-brown eyes peering into empty holes gouged into flesh, "I was too weak, too soft, too selfish." Tsuna reached up to run a hand through soft curls, and was disappointed (but not surprised, because Lambo always disappeared after Tsuna pleaded for forgiveness, but always returned again) when Lambo dissolved into dust and sand, and a younger boy with lily-pad eyes and a mischievous smile took his place.
Tsuna had raged and stormed and wept a thousand tears after Lambo's death (too young, he thought bitterly, at Lambo's funeral, and realized this was the first time he had seen such a peaceful expression on his face, gossamer-green eyes closed), and cursed himself a thousand times for picking someone so young and bright and fragile. The callous killing of a guardian who was naught but a child opened his eyes to the truth of the mafia, and Tsuna nearly went crazy with rage and desperation and helplessness, until Gokudera (Thunder and storm are brothers, Reborn had once told him, and Tsuna remembered this as he looked into Gokudera's blank face and flaming eyes as he held him back from a suicidal rush into the Millefiore base and whispered 'Not yet, Tenth." with an eerie coldness that spoke more about his hatred than any explosion of anger ever could.) grounded him and wrenched him out of his stupidity.
Tsuna took Lambo's ring and wore it on a chain next to his heart, to remind him to never again make the mistake of being selfish enough to take away a childhood.
"Eh? Tsuna-nii? Lambo's hungry! Buy me a lollipop, Tsuna-nii!"
Lambo jumped up, eyes wide and sparkling in glee, all energy and raucous smiles, and Tsuna's heart ached for the past, a time before death and destruction and hatred. "Come on, come on, come onnnn, Tsuna-nii. Lambo-sama's hungry!"
"Forgive me, Lambo." He murmured wistfully, eyes fixated on Lambo's miniscule body (and he had always wondered how such a small body could hold so much strength). "For everything."
All his guardians had woken up after Lambo's death, and strengthened themselves, following after Tsuna's footsteps. Gokudera blew through enemies with an ice-cold logic that belayed his cold fury, and Yamamoto rained down destruction with the tranquility of a hardened, unleashed killer. Ryohei burned a thousand times brighter with anger as his fuel, and even Mukuro, after hearing of the youngest Guardian's death, smiled chillingly and began to set up illusions so gruesome that they drove men to madness. Hibari seemed wholly unaffected, (but Tsuna could feel the stirrings of vicious anger within those gunmetal eyes, and, true to his predictions, Hibari went out and single-handedly massacred the men of seventeen Millefiore bases the day after Lambo's funeral) but never-the-less grew unerringly stronger.
After a year, they rained retribution upon the Millefiore with such mind-blowing strength that even Byakuran, of the infinite knowledge and impossible strength, fell under the might of the Vongola, blown to pieces by the hatred of the Storm and burned to ash by the hand of the Decimo. Tsuna burned the Millefiore headquarters to the ground, and then, the midst of scorched earth and surrounded by the smell of fire and death, he erected a tower of blood-tinted ice that looked unerringly akin to a lightning pole (for Lambo, he had whispered as his guardians looked on with knowing eyes as the tower shimmered a light green in the midst of the forest). Byakuran was Tsuna's first kill, and one of the only ones he did not need to forgive himself for.
"I forgive you, Tsuna," Lambo replied, uncharacteristically quiet, looking up with ancient eyes for a moment that seemed like forever.
"But don't forget to bring Lambo-sama candy, Dame-Tsuna." Lambo added, breaking out in a lopsided smirk-smile, and Tsuna was reminded briefly of sunshine and laughter, and of brighter days.
Three hours later, when Xanxus noticed a bag of grape-flavoured candy and a lone lollipop sitting on the Decimo's desk, he did not challenge Tsuna (because who would be cruel enough to question a boy-man with weary eyes that had seen too much and smile that was fragile as china-glass) when he told Xanxus that the candy was just a whim.
Just a whim, indeed.