There was a time when L celebrated his birthday. He remembered it, if vaguely: parents, a cake, the usual sort of thing. Although perhaps he'd made it up, taken popular images of child birthday and made them his own. It was possible; L was rational enough to admit this. But he preferred to think of the memories as genuine, to believe that he'd once had parents who cared about him.
Birthdays with Watari were different. At first, they were merely understated: an occasion marked solely by candles on his cake and perhaps a gift of some sort. There were no parties and no one else was ever invited. Birthdays, like all other occasions in the Wammy household, were strictly a private affair.
Once he began collecting other orphans, even this small marking of the significance of the day was abandoned. They might be only children, but they were also security risks, as their biggest failure made clear. L couldn't trust them to keep the secret of his birthday, couldn't let any of them that close to him. So his birthday passed like any other day, subsumed into the more general holiday of Halloween, and he let it go with no protest. L saw no point in protesting something he knew was necessary.
If he ate cake on the day, well, he often did that, so it wasn't something anyone would remark on or remember. If he seemed lost in thought or smiled to himself, again, it wasn't unusual. By the time he was an adult, L sometimes thought even Watari had forgotten the date of his birth.
But L didn't forget. He kept track of each birthday with an almost morbid fascination, wondering how long he'd live, if he'd see another. He knew well that his job was dangerous and even better that he wasn't immortal. If he had doubted either, the mere existence of his successors, just waiting for him to fail, made the situation perfectly clear.
This particular birthday, L thought he was closer to death than he'd ever been. Even as they were closing in on Kira, he knew that the original one was right next to him, close enough to touch, for all he couldn't prove his guilt. He looked at Light next to him and smiled to himself as he ate the cupcake he had requested.
"What are you smiling about? The case?"
"Nothing," he replied, while he thought, Will you do it soon? Will you let me live another year? It seemed unlikely. L found he was almost looking forward to it; he was bored with the current stalemate between them. At least he would finally know that he was right, see the 100 certainty before him, that moment of clarity that usually preceded the end of a case, though this time the resolution would be more final. You will condemn yourself, he thought, and it was almost enough.
"Happy Halloween, Light-kun," he said, though he knew the holiday likely meant nothing to him. Likely meant nothing to any of those around him. If he'd told them it was his birthday instead, that would likely get a reaction, though he expected that they wouldn't believe him. At least Light wouldn't, reasoning that L wouldn't tell the truth, wouldn't give them information that might be a key to unlock his secrets. The others might, but they didn't matter. In the end, this was between L and Light; the NPA officers had become merely extraneous baggage, a burden rather than the allies he'd hoped for.
Happy birthday to me, L thought as he finished his cupcake, wondering when Kira would deign to give him the only gift he was capable of giving.
