I still don't understand what the whole deal is with the gaster follow head is- like, something about it ending up in canon?? I must understand-

To explain:

The third Gaster follower in Undertale appears as this gray shape that looks like a huge humanoid head:

And most fanart has depicted it that way. However, in Dogs of Future Past, I decided to take a different route, and interpreted it as a kind of large-headed bird monster: 

And THEN we got to Deltarune, and see this guy:

So basically, my interpretation of that follower as a bird with a big bent head, instead of just a huge humanoid head, ended up being canon!