The AU's present are:
The older brother of Sans and Papyrus. He is a scientist who fell into the void first. He blames himself for everyone being trapped there. Referred to as Wingding, he is the shortest and youngest of the group. The majority of the time, Wingding is trying to find a way out of the void. Experiments going wrong infuriates him and he likes personal space which causes friction between him and Swap.
Underswap Sans and Papyrus are his sons. He was the Riverperson before falling into the void. Swap is extremely optimistic about them escaping the void and takes photos of the rest of the group to show his boys when he comes home. He cooks and takes care of the house. This version of Swap!Gaster is not canon to the Underswap game as that version of Gaster remains unswapped. He hates smoking, swearing and liars but loves hugs.
General of Asgore's army, Fell spends most of his time fighting the 'anomalies' from the positive void. Culling these creatures protect the worlds that spawn them. The rest of the time, he watches TV with B. He is the adoptive father of Underfell Sans and Papyrus. He smokes and swears which often results in him being thrown out into the void by Swap.
Stars is the tallest of the Gasters and is a scientist like Wingding. He is the oldest of the Gasters. He spends most of his time as an assistant to Wingding and reminds him of when he needs to sleep and eat. Outer has a caring and fatherly attitude, similar to Swap but calm rather than energetic. He sees the funny side of experiments going wrong.
Newtale is Bunnymuse's own AU. B or Blindy (or ?????? in the infobox image) tends to not be very active with in the home as he's mostly blind. He used to have a tail and has a damaged soul.
Swapfell was formerly part of the group through manipulation and deceiving. He was removed after his intentions were revealed.