Fred. Because of the bizarre nature of the character and his expressive movements, people have been wanting to see more of the him. When Randy posted a single video of him just simply talking to Fred, entirely out of character, viewers found it absolutely hilarious. This lead to Randy posting 2 more equally popular videos, with Fred being portrayed as more of a character who suffers from depression to add some layers to him.
Trey gets a lot of this treatment as well. When Randy let him do his own episode on Thomas the Tank Engine, some felt like he was the more interesting and expressive host. When Randy went back to taking the reigns as host, some viewers kept asking when Trey would do his next video, which wouldn't happen until I Have No Mouth and I Must Scream over 6 months later.
Fred's Henchmen named P and Zuvy. The fact that this tiny bird in a cage needs two guards has caused a few fans to form entire theories as to what Fred's real occupation is. The two carry Nerf guns and ham it up to the camera, especially P. When P's character finally spoke in the season 1 finale of 2Beats+, fans wanted to see more of the him.
No Such Thing as Bad Publicity: Except maybe actually so. The Lost Media Chronicles episode about Christine Chubbuck was perceived by many viewers as actually claiming to contain her infamous suicide footage, getting massive dislikes and accusations of clickbait. Shoegazer had to put a large disclaimer in the video's title. When the video was pulled in 2017 by YouTube, Randy took the opportunity to re-edit it in order to make it seem less like clickbait.
Fred was like this for a while for new viewers. His obnoxious attitude and the fact that he seems to slow down more videos than he does actually add to them certainly doesn't help matters. However, it seems like more people have warmed up to his presence if the newer videos are an indication of anything.
The same cannot be said about Stan the Banana Man. Introduced as a character that would allow for Randy and Jordan/ Trey to review indie artists, fans hated him for his Totally Radical talk and for being an eyesore. The fact that his jokes often fell flat made some of his appearances drag. When Randy killed the character off in the Wolfenstein episode, fans were still pissed because they didn't wanna see him come back, even if he was going to be killed off. The character is that widely disliked.
Jordan, the original co-host in 2Beats+ for having a rather weak delivery and seeming to do little else but parrot what Randy has already said in the review. Say what you will about Trey, but at least he added something to the reviews.