Fossil is an infamous sperg, sperged too hard, and got into arguments.
Another sperg, Kamui, AKA mannequin molester, decided that he was in fact the better sperg and thus started shitting on Fossil which resulted in the great Sperg-Off. Unfortunately for Kamui, he was proven to be the dominant sperg and it forced Fossil off of Pregchan for a while.
When Fossil came back, he started drawing Cookie Run characters in relative peace. But because other spergs now see him as cheat bait, they try to piss him off and it doesn't work, resulting in more Cookie Run art.