A/N: YO! Here's another heart-breaker for you guys! This takes place a few hours after the AWESOME Cosmic Ocean episode, which addressed something I think most of us within the fandom have pondered over at some point during Season 4.

I hope you like it!

I OWN NOTHING!

Pillar

It was a few hours after they'd left the vast and beautiful Cosmic Ocean of Varuna, the Heart of Darkness fragment stored safely on-board the Ulixies, that Donatello had woken up in the middle of the night (in Earth hours anyways) due to a 'Bad Feeling'.

Well, to be accurate, it was more of an 'Unpleasant-Feeling-Of-Knowing-One-Of-Your-Brothers-Is-Up-To-Something', but it was a bad feeling all the same. And it was more than enough to get Donnie out of bed, nearly tripping over himself with untangling the blanket from around his legs, and sliding open the door to his quarters before tiptoeing out of the room and into the dark, eerily vacant hallway.

As far as he could tell, the others were still asleep; he could hear Raphael's faint snoring in the room beside his, followed by Casey's incoherent mumbling – 'Why're giant alien worms always tryna eat me?' –and he could hear the sounds of Michelangelo still messing around with his T-Phone. He quickly took a peek into April's room to find that she was just as dead to the world as Raph and Casey were, though at least she looked more like an angel than a drooling star-fish. Fugitoid was still on the bridge, on 'autopilot', practically driving the ship in his sleep. So that left only one more person…

Donnie frowned. "Leonardo."

Being mindful not to wake anyone else up, Donnie marched towards the holo-room, his brows knitted together and a scowl creasing his features. He loved his older brother, of course he did; words could never truly convey how much he loved his family. But still, there were times in which Donnie wanted nothing more than to wring his leader's neck and strangle him for his stupidity, and he had little to no regret in admitting that he felt as such more often than he really should. But in this case, his feelings were justified.

Leo knew what he was doing was wrong. He knew it was doing him more bad than good every time he went in there to talk to a person, a figment of his imagination, a person who wasn't truly there –

He'd stupidly allowed Leo to continue with it at first, thinking that it was probably the best way his older brother could really cope with…well, everything. But now, it was going too far, and Donnie couldn't allow it to go on any further. This had to stop, tonight.

Donnie made it to the holo-room just in time to catch Leonardo once again in the simulation of their old dojo, sitting with his legs folded beneath him and his back erect in front of the image of their beloved Sensei, who smiled down at his eldest son as he reached out and laid a clawed hand on his shoulder, the same indescribable, unconditional love and affection gleaming within his dark red eyes.

Frozen in the doorway, Donnie stared.

It was as if he'd never died. It was as if he was truly there, right in front of him, close enough to touch, to hold and never let go. And it was almost enough to make Donatello crumble right then and there as his eyes watered, a lump forming in his throat.

Father…

But then the simulation ended, the pixels fading into nothingness as the white, pristine walls of the holo-room returned, leaving Leo sitting alone in the center of the empty room. And with a hard blink, Donnie remembered the very reason why he'd come here in the first place.

The damn holograms…

Squaring his shoulders, Donnie marched into the room, stopping only meters behind Leo, who had yet to turn around or even acknowledge his presence. Which, again, was pretty worrying. "Leonardo."

The other turtle barely reacted, other than to subtly turn his head in Donnie's general direction. And when he spoke, his voice was low, hoarse…

"Hello, Donatello."

…and emotionless.

Repressing the shudder at the pure soullessness of his older brothers' tone, Donnie frowned deeply. "Listen, the others told me that I shouldn't really say anything, but seriously, this is going too far," he stated bluntly, fighting back the urge to grab Leo by the shoulders and turn him around to face him, dammit. "I mean, I get it Leo, I really do, believe me. But this…this isn't coping anymore. This is borderline unhealthy, not just for your emotional state but your mental state. You know that, right?"

"Hm," was Leo's quiet reply, followed by a light shrug of one shoulder.

Donnie's frown deepened. "Think about it, Leo," he pressed on, "if you keep this up, keep going to places and talking to people who aren't really there, you'll start to believe that they are; your mind won't be able to differentiate the illusion from reality, and that will take its toll on you, turn you insane. And on top of that…"

He took a breath, his frustrated frown melting into sadness as he stared at the back of his brothers' shell. "…talking to 'Splinter' like this…it's not good, Leo. I know, I miss him just as much, but…this isn't right. Not for you, or the rest of us," he said, twining his fingers together. "You understand that, right?"

Leo said nothing. Instead, his hands tightened into fists on his lap.

At his brothers' silence, Donnie dropped his hands to his sides again, staring disbelievingly at the back of Leo's shell. He then narrowed his eyes, a growl rumbling from the pit of his throat as the urge to smack him upside the head with his staff became harder to quell. Here he was, trying to help Leo, to bring him out of his shell, out of this dangerous hole he'd dug himself, and yet he refused to even look at him? What the hell?!

Finally, he'd had enough, and he balled his hands into fists as he stomped closer. "Dammit, Leo! Are you even listening to me?!" Donnie shouted, reaching out to grab Leo's shoulder. "I'm trying to tell you that this isn't –"

"LEAVE ME ALONE, DONNIE!"

He'd underestimated Leo's reflexes, a grave mistake on his part.

The moment his fingers brushed against his shoulder, Leo's hand uncoiled and struck out like a snake, grabbing Donnie's wrist in a vice-like grip before he shot to his feet and spun around to glare at Donnie, his teeth ground together and his pupils dilated with fury. His other arm was held up, pulled back, fist clenched and ready to strike.

Donnie dared not move, nor did he even attempt to rip his hand from Leo's crushing hold as they stood there, his older brother continuing to glare at him as though he were an enemy. In turn, Donnie stared at Leo, his brown eyes widened and his free hand trembling at his side.

Donnie couldn't remember a time he'd been afraid of Leonardo. He'd been afraid for him more times than he could count, and at times he'd even been a little intimidated. But never had he, or any member of his family, had any reason to fear their brother, their leader, their protector, even though they'd never asked him to be.

But now, for the first time in his life, looking into the unfamiliar, rage-filled gaze of the one he loved and admired so much…Donnie was terrified.

He blinked rapidly, praying that this was all a dream, that he was still back in bed having a nightmare, or that this was the holo-room malfunctioning or something. Alas, he knew an illusion when he saw one, and this was certainly no illusion.

"…L-Leo?" he stammered.

And suddenly, as if a light had been switched on in a dark room, Leo blinked once, and the glare was gone. His arm lowered, eyes returning to normal, though clouded with confusion as he stared at Donnie's fearful expression, before looking down at their hands. Then his eyes widened in horror, a sharp gasp escaping him as he promptly recoiled, releasing Donnie's throbbing wrist as he took several steps back, his face twisted with mortification, before he turned his shell on him yet again.

Another long silence hovered over their heads as Donnie watched Leo, cradling his aching hand in the palm of his other.

He'd feared this sort of thing would happen. That Leo's frequent visits to the holo-room would not only mess with his head, but with his emotions too, making him more prone to unmotivated bursts of anger or moments of intense depression. And Donnie had just experienced the former first-hand.

Swallowing thickly as the silence became too much to bear, Donnie spoke again. "…Leo? Are you…are you okay?"

He wasn't okay. It was painful how clear it was that Leo was not okay. But he figured he'd ask anyways.

However, much to Donnie's surprise – and further concern – after a moment, Leo turned around to face him again. And he was smiling.

"Yeah, Donnie," he said. But though his smile was pleasant, as if he were relishing in the wonderful weather they were having this evening, there was pinch of annoyance laced within his chipper tone.

"I'm okay. Better than that, I'm great," he continued, his smile slowly forming into a thin line; not quite a frown or smile, but enough to give Donnie a reason to be cautious. "Wanna know how great I am?"

"Leo –"

"Why, I'm so great, I've made my whole family worry about me for the past few weeks," he interrupted, his smile finally disappearing altogether, replaced with a scowl. "I've been slowly driving myself insane, even though I know that this is wrong, that it's not healthy, but I do it anyway. And even though everyone knows I'm not okay, I've been trying to keep it under wraps because I don't want to throw any more stress on the team since we, y'know, only have so many weeks left before the world ends up getting destroyed again, and it'll all be on me if we fail. I'm trying to be there for everyone, to stay strong and be the leader that Splinter wanted me to be, be the brother you guys need me to be, and yet here I am outright attacking you and yelling at you because I'm just so damn amazing right now –"

Whatever he'd planned to say next, Donnie would never know, nor did he care in the slightest as he lunged at Leo, throwing his arms around him as they stumbled unsteadily to their knees, burying his face into the crook of his shoulder. Leo went very still in his arms, but Donnie only tightened his hold, squeezing his eyes shut.

Donnie had seen Leo cry only a few times in his life. But no matter how many times he saw the tears running down his face – tears he hadn't even been aware were falling – it filled him with an unquenchable rage, a need to go and punch the lights out of whoever had dared to hurt his older brother. In this case, however, he could only hold him as close to his heart as was physically possible.

"Leo…it's okay," he whispered, his cheek coming to softly rest against Leo's tear-stained face. "I know you're trying. You're trying so hard to be there for us, to keep it together for our sake rather than your own, and for that, we're all grateful. But you don't have to do this to yourself. You don't have to keep your own feelings locked down. You don't have to keep carrying the burden all on your own and you don't have to be a hero all the time. Mikey, Raph, Casey, April, Fugitoid, me – we're all here for you, too."

He felt Leo slowly relax in his arms, but his shoulders were trembling. Even now, he was still holding back, for Donnie's sake as well as his own. In truth, Donnie wasn't sure if he could take it Leo crumbled now…but he had to understand. He had to let go. He had to…

Tightening his arms around him, Donnie swallowed the large lump in his throat. "You're really good at what you do, Leo," he continued softly. "You're an amazing leader, better than any of us could ever be. And I know I couldn't ask for a better big brother. But let us help you, Leo. Don't do this to yourself anymore. Let us help you."

At that, it was if a dam had broken as Leo's breath hitched once.

And then, at long, long last, Leonardo buried himself against Donnie's chest and sobbed, tears cascading down his face as he latched onto Donnie like a scared child in the dark. All the while, even though his own heart shattered to pieces at the sound of his brother wailing against him, Donnie didn't remove his arms from where they remained locked around his older brother.

Leo needed this. Leo needed him. And now more than ever before, Donnie was more than willing to be there for him, to be that pillar of strength for the brother that had always been one for him, for all of them, even when he'd been on the verge of crumbling himself.

"I-I'm sorry, Donnie," Leo wept, his voice small and weak and so broken that it killed Donnie inside. "I'm s-sorry, I'm so sorry –"

"Shh," Donnie soothed, bringing up a hand to cradle the back of Leo's head. "You don't have to apologize for anything, Leo. It's okay. It's okay…"

And it would be okay. They would find that last fragment, destroy the Heart of Darkness, defeat the Triceratons, and go home. And they would finally see Splinter – the real Splinter –again.

Donnie swore right then and there, as he held his sobbing big brother close to him, close to his heart, that everything would be okay.

A/N: So. Much. Feels!

I hope you guys enjoyed this one, and more are on the way!