Foreword:
I imagine any sizeable group of people-who-lived would get together, have a few drinks, and do a competition to see whose Voldemort died in the strangest way.
This Neville's universe's point of divergence from Canon is simple- The Potters gave birth to a girl instead of a boy. Since the wording of the prophecy implies that the Chosen One is male, Voldemort tried to kill Neville instead of Rose.
Tom ways to Die
So there I am, with Rose Potter, Ron Weasley, Hermione, Ginny, and Luna. We're on a running chase through the Department of Mysteries, with the Lestrange brothers and Bella Black hot on our tails. We take a sudden left turn down a side corridor so as to shake them off for a bit, but we wind up in this dead-end with a locked door. Bella rounds the corner, and she's, as the Americans say, fucking pissed. I guess she could have been the normal kind, but her aim was way too good. Anyhow, Black does the obvious thing and throws a killing curse right at the middle of our group. We scatter like we practiced doing, and the curse hits the locked door.
Now this was obviously protected by some heavy-duty enchantments- Lord Black's knife glanced right off of it when we tried to get it open. But it wasn't designed to withstand unforgivables, so it splinters inwards. That's when the shite hits the fan. Rose turns to me and says, "Nev, you aren't going to believe this, but the room's bright pink and filled with love potions!". (1) I have a look, and she's right. The place puts Madame Puddifoot's to shame. At that point we all have bigger things to worry about- There's a massive swarm of Cupids pouring out, and golden arrows are flying everywhere. You'd think they'd go after us first, since we were closer, but Bellatrix and the Lestranges are actually the quickest to go down. They end up looking at each other with the sappiest expressions, which is even more disturbing than you'd imagine.
We decide to book it, and actually make it pretty far, since the Cupids have a bunch of targets in the form of the other Death Eaters. By the time we make it to the Ministry atrium along with the rest of the Order, it's a literal orgy down there. We had to foot the deep cleaning bill for the Unspeakables, which was awful, but I digress. Voldemort finally shows up, duels Professor Dumbledore, and goes after me through my scar. That's when one last Cupid, which must've snuck out through the elevator shaft, hits me with an arrow. Since I'm being possessed, Tom gets the full effects and kinda self-destructs, taking his Horcruces with him. (2) I suddenly realized that Rose Potter is my soulmate, but we were already a thing, so it didn't really make a difference.
Professor Dumbledore was absolutely insufferable afterwards- he kept going on about how he knew that Love was the "Power He Knows Not", even though nobody could have ever predicted what happened down there. Anyhow, that's probably the strangest way a Voldemort ever died. I'd like to see any of you top that.
(1)
This is a canonical room in the Department of Mysteries. Dumbledore mentions it at the end of OOTP, and Rowling gave more details in a Pottermore article.
(2)
The plural of "Matrix" is "Matrices", so the plural of "Horcrux" should be "Horcruces".