Oswald is some annoying octopus who is obsessed with rollerskating. He however, has an irrational fear of Squidward Tentacles. He hates him with a passion because he claimed to be a blue "octopus".
Due to this, Oswald developed the habit of rollerskating over people, especially Squidward Tentacles.
He is also a member of the Satanist Empire and abandoned his other friends on Earth. He often has tea with Scanty, Kneesocks, and Tsunami. Oswald later fell for Kneesocks and thus, got married, and the latter did in fact love him back for obvious reasons, due to the fact they're different species.
Oswald uses his tentacles to tangle his victims and..... yeah you probably know by now.