How to Change the Future

Hiccup is from a post apocalyptic future is sent back in time to change the past in order to prevent the world from ending he must protect 4 girls and stop a war this story will many other crossovers like HTTYD,FROZEN, ROTG, TANGLED, BRAVE, MR. PEABODY & SHERMAN and more (harem) {hiccup,elsa,anna,astrid,rapunzel,merida}