The current relationship between WWE and The Ultimate Warrior began back in July of 2013, when Warrior met with Triple H on the same day that 2k Sports announced Warrior's inclusion in the WWE 2k14 video game.
From there, Warrior then met with Vince McMahon during SummerSlam weekend, and what was supposed to be a 30 minute meeting ended up with the two talking for over 2 hours.
Following that meeting, WWE began working out a deal with Warrior, which the two sides ended up completing in December.
Subject: When Did Ultimate Warrior and WWE Begin Negotiations? 
