Sans has gotten himself stuck in the void between worlds in a successful attempt to stop the resets of his timeline. He's not sure how long he's been chillin' alone there, but eventually a chance at escape stumbles his way in from the Veil of Death. His name?—Sirius Black. (no pairings)

Kris and susie travel to mt. Ebott and fall into the undertale timeline/universe

25 years after the pacifist route today was Firsk’s 25th birthday and Toriel was going to head to the grocery store but she never came back and Firsk was on her way to find her but what she stumble upon was a old wooden workshop that seemed abandoned for centuries...

At the end of the Genocide route, Sans dies. Something changed along the way, a white hooded woman strikes a deal with Sans that'll set him free from the Resets. (Disclaimer! I don't own anything here. UNDERTALE belongs to toby fox while RWBY belongs to Rooster teeth and Toby Fox!)

It has been a couple years since the monsters reached the surface. Inter-species relations are decent, and everyone is happy. That is, until one day, when an unfamiliar door appears in the Dreemurr home. A gateway bridging two worlds that never should have touched. What happens when Frisk decides to enter the door?

Undyne, Heroine of the Underground and the Spear of Justice, is reborn into the Japan of My Hero Academia. On her journey to become a hero, she'll show the world just how determined monsters can be.

After the Genocide Route, Sans dies. He expects a reset after that, and for everything to be normal again. But instead, Sans wakes up in a strange world where humans can use magic, almost all monsters are evil, and demons exist. He meets a wizard guild, Fairy Tail, and things go insane when he joins the guild. How will Sans fair in this world?

After being missing for a month, Remus Lupin's twin sister returns with a brand new set of...interesting...friends. After spending the rest of the summer hiding his true identity from his new family, Remus and his friends find a new subject on their Hogwarts timetable for their fourth year and the professor is all too familiar to the young lycanthrope.