#1 Immediate rivalry with main card babyfaces
The WWE Creative must not put The Fiend in the feuds with a big babyface Superstar in the near future.
The Creative should put him in the storylines with the mid-card wrestlers, in which he can torture them for a long time and make them look pitiable. If necessary, the opponents should be granted wins only via DQ, where The Fiend lets and disqualifies himself.
This will generate sympathy for his opponents, and prepare The Fiend's character for the main event. Him targeting more than one mid-card wrestler at the same time can also be a good option.
As we all know, the storyline with babyfaces won't end until The Fiend is defeated clean a few times. After being pinned by a babyface, the devilish character will lose its charm and people might not take any interest in the further storylines. So, the WWE should not show any urgency in this context.