#4 History repeating itself?
It's a norm in professional wrestling that an angle that works and engages the fans is bound to be replicated in the near future. For example, Austin's beer bash on the road to WrestleMania 15 was followed up by Kurt Angle's Milk-O-Mania around two years later.
Remember the D-Generation X reunion from 2002, when Triple H turned heel and betrayed Shawn Michaels? Soon after, someone attacked Michaels in a parking lot and Triple H suddenly became sympathetic of him.
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This continued on for a while before Michaels presented the CCTV footage on an episode of Raw and revealed that it was Triple H who attacked him.
This story seems eerily similar to the DX one, with Joe wanting to destroy Reigns, and suddenly feeling concerned about him after the accident. It seems like Joe is involved in what could be a sinister ploy to take out Reigns, playing babyface only for a while, before he strikes at the right time.