>>531955215
What evidence? Literally all that FRIEND has done is appear in places and laugh.
Yes, his laugh is similar to the Knights, but that could easily be explained by the Knight's power coming from FRIEND.
The idea that this thing is somehow going to matter to the main storyline has no evidence. The "that chair will kick your ass" thing could just be talking about the ERAM stuff since that's also tied with FRIEND things. LIke how the other gacha messages tie to the side stuff of Chapter 3 (most of the others guide you in the Egg stuff).
FRIEND has NO actual presence thus far in the main storyline. He's far too complex of a thing to make a big deal in the more grounded drama around the townsfolk and Dess. Especially since Gaster's already going to be a weird thing present in the "normal" story eventually.
>>531955458
The difference is that Flowey established himself form the start. He introduced himself and showed he's got more to him, so seeing him following along was more of a "oh yeah, that guy, what's he doing" thing.
FRIEND isn't something the characters know about at all yet. He's literally used to represent a generic idea of a Darkner in Ralsei's explanation. And that visualization is something (YOU) see, not the characters.
He still probably is pulling shit behind the scenes, but I don't think he's going to spring up and be the final boss in the normal path of the story.