Never Leave Again (Shape Island)

Taking place a year after the events of the episode of Shape Island "Creepy Cave Crawl." Ever since Triangle left behind his subjects, AKA the monsters in the cave he used to hang out with the monsters in when he was formerly known as the king of Halloween, they have been upset and wanting their revenge on Circle and Square for "stealing" Triangle from them, especially Susan. As a result, one year later, the next Halloween, the monsters decide to get revenge on Triangle by pulling him back into the cave and trapping him in there. After finding out what happened to him, Circle and Square now have to rescue him... while also finding out about their hidden love for each other. Meanwhile, Triangle meets some new shapes named Rectangle, Hexagon and Octagon who live in the cave and have been living in there ever since they got stuck in there... and Triangle ends up finding out that there's something growing between him and Hexagon besides friendship. Triangle, in an attempt to not give in to the monsters's demands, decides to go against them to prove himself to be free from them for good with the help of the other shapes. However, will Circle and Square be able to free their beloved friend from the cave? Or will Susan be able to stop them? And what of Susan? Is it possible for the Halloween Triangle to ever win out against the monsters in their dark cave forever?

(Oh yeah, and PS; I ship Circle X Square so you're going to be seeing my ship in this fanfic. And I also have an OC X Canon ship of Triangle and my OC, Hexagon. Prepare to see those ships in this fanfic. Enjoy!)