#2 There are other Superstars that could play a part in this feud
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While we are discussing the rivalry between Joe and Rollins, the scope of the story shouldn't be confined to those men. Other characters have been involved previously, with Triple H and Stephanie McMahon being antagonists to Rollins’ protagonist, affecting his hope to reclaim his main event status.
So others that have had issues with Rollins or Joe in the past could provide backup, and in the process, all are elevated. For example, Finn Balor has had his share of issues with Joe during their time in NXT.
After months of defeating Joe, Balor eventually lost the NXT championship to him, never to regain it. Joe hasn't had many foes since being on Raw, but involving Balor could lead to Bray Wyatt being added.
In the past, Rollins has had his share of issues with his former Shield colleagues, but this could be a time where he doesn't have to fight alone, and as a result, those around will also receive attention.
Major rumor about recently released stars HERE