... the children went to confront IT with a silver slug and a slingshot and if Richie Tozier hadn't screamed "It's the werewolf!" IT would have shown up in some other form and they'd have been screwed but he did and they hurt IT and IT fled but they didn't kill IT that way and went into the sewers and the tunnels below them to finish IT off and IT was scared of them then because they were willing to confront IT and that's the biggest weakness of a lot of childhood fears, isn't it? IT tried to use The Creeping Eye from some recent (at the time) horror movie and one of them had really never seen what was scary about the movie monster, so while the others were petrified he just laid into it: "Come on! What's the matter with you lot? I'm doing the mashed potato all over this thing, and I've got a broken arm!"
They tracked IT down in ITs lair and IT tried a bird form because one of them had been scared of birds ever since one landed on his pram, but the bird-lover drove IT away with the names of wonderful birds that really did exist and the fact that it didn't.
I can't remember exactly what IT was and what they did to IT, but they hurt IT badly and left, then got lost in the dark tunnels until Beverly regrouped them by having sex with them all.
Then, thirteen years later, or maybe twenty-six because IT missed a cycle, stuff started happening again and the one who'd stayed behind to tell the others if it did called them all back, and one of them slashed his wrists in the bath and scrawled:
IT
on the wall in his own blood rather than face IT again.
I'm pretty sure Bill, Ben, Bev and Richie came back to join the one who'd stayed (can't remember his name) and maybe it was Eddie who didn't because IT bit his arm off when he shoved his inhaler into ITs mouth and hit IT with a throatload of battery acid so maybe that happened when he was a kid and that was why the group was falling apart before Bev got them all back together.
Henry the psycho got let out of the madmanbin by IT in the guise of a giant Doberman and got a ride back to town in Christine, and I think he grabbed Bill's wife and handed her over to IT and Bill had to zoom down the street with her on the back of his old bicycle (that could race to beat the Devil, remember?) to snap her out of the trauma of looking into IT's deadlights ... whatever deadlights are.
*headscratch*headscratch* I think it was the bird-lover who slashed his wrists. I think he'd been the one who knew about animals and realised, while they were down there the first time, that IT was female, pregnant and very near her time. When they went down the second time, IT was, eventually, a spider with a huge web with bodies hanging in dusty silk all around, and after they killed it they went back where it had dragged itself away, stamping on all the eggs they could find ... but they never could be sure they'd got them all.