What will happen when an antagonistic side character form an alliance with the losing heroine?

Note:
The story takes place after the events of the cancelled series "I'm Just a Side Character in a Dating Simulation". The chapter is incompleted because we took it from the author's Weibo (Chinese social media). Unfortunately, none of us could get our hands on the doujinshi.

The original series was tagged as harem, but the author actually confirmed over and over again that the harem is a "lie".