This community is scary good, so I don't like my odds here :p
- Wammy's House always changed names to protect the innocent. L is unique in that he arrived without a proper name.
- The destruction that went down in L's backstory was so complete that sticking with "L" was fine. Or that's Watari's rationalization. More important is that L insisted.
- The place quietly began to revolve around L from the moment he arrived, and most of the kids got transferred to other branches, but the succession program didn't start up until L was eleven and he and Watari had a very narrow escape.
- Watari was definitely the guy in charge of the succession program. He's the one who thinks the world should have as much L in it as possible. L tends to think (with quiet pride) that one of him is sufficient.
- It's rocky at the top, as we know, but being in the middle of the pack at Wammy's basically sets you up for life.
- After A died and B ran away, Matt was actually the top contender for a brief time. He was entirely happy to cede to Mello, which is why they get along so famously.
- Near arrived a year after. You can guess how that went down.
- Near was wholly confident that he could be L, pure and simple. Then the Sakura Incident came and knocked a healthy dose of humility into him. Mello did not catch on to this development in his character.
- If Light were permanently stuck without his memories, he would have become the legitimate successor in the end. And Mello... yeah, he might take that even worse than he took canon events.
- Political networking was the most agonizing experience of Near's life.
- Rules particular to Mello's mafia: do not use fake IDs for leverage, do not touch the Cadbury's, and above all do not complain about hearing Eye of the Tiger by Survivor a few too many times.
- If he and Mello had both survived, Near would have gladly given up the gig. The only reason he doesn't in canon is that a world with no L in it just doesn't sit right with him.
- Needless to say, Mello would have made a highly in-your-face L. Think of Cormoran Strike having that conference with the Universal Humanitarian Church as a baseline.