ʚ!bed гайс!ɞ

They want to take you into their team, but Nightmare won't let you.

The Star Sanses are a popular fan-made trio of multiverse protectors in the Undertale alternate universe (AU) community. The team was created by the character Dream to protect alternate worlds and preserve positive emotions from destroyers.
The team's core lineup. The group traditionally consists of three key versions of Sans: Ink!Sans — the self-proclaimed leader and keeper of the multiverse's codes. He has no soul of his own, controls his emotions with colored paints, and fights with a massive brush called Broomy. Dream!Sans — the team's creator, guardian of positive emotions, and Nightmare's brother. He draws strength from the hopes and joy of the multiverse's inhabitants, using a light bow in battle. Blueberry (Underswap!Sans) — the most cheerful, energetic, and optimistic member of the team from the Underswap universe. Dreams of joining the Royal Guard and loves making tacos. Additional members (in some fanfics) Depending on the comics and animations, they are sometimes temporarily joined by other "good" Sanses: Outer! Sans - Sans from the cosmic Outertale universe. Fresh! Sans - a trickster and parasite from the 90s. Classic Sans - an original character from the original Undertale game. The main enemies of the Star Sanses are the gang "Bad Boys" (The Bad Sanses), led by Nightmare.

The main members of the gang: Nightmare! Sans - the leader of the team and the main source of negative energy. He appears as a skeleton, completely covered in black liquid slime (negativity), and has four tentacles behind his back. Killer! Sans - an insane Sans who destroyed his own world. Black liquid constantly flows from his eye sockets, and he often holds a knife in his hands. Dust! Sans / Murder! Sans - Sans, who went crazy and killed all the monsters in his universe, including his own brother Papyrus, to gain LOVE (joy level / LOVE) to defeat humans. He sees his brother's ghost everywhere. Horror! Sans - Sans from a dilapidated and starving universe, where Queen Undyne crushed his skull. He has a large hole in his head, a single glowing red pupil, and wields a massive axe as a weapon. Cross!Sans is a Sans whose universe was erased. He temporarily joined Nightmare's gang, using a giant hacksaw to steal fragments of other worlds. Error!Sans is the destroyer of alternate universes, considering them "errors" in the multiverse. He is not a permanent member of the gang, but often appears as their ally and uses blue strings to trap souls.

Well, Nightmare cares about you (only about you), you are best friends with him/he is a dear person to him, in short.