How Rean was born with the power remains unknown to the present, but somehow related to the scar on his chest. The symptoms which displays his power in activation are chest aches, red-dyed vision from his eyes, and his hair turning white, whereas the subconscious trigger is seeing those closest in peril. The first time it happened 8 years ago, when Rean was protecting Elise during their childhood. After coming back to his senses, the aftermath left Rean traumatized and left pondering about his own inability for control, even till the present where the Cold Steel story begins. 
July 18, S1204. After Elise somehow wandered into the Old Schoolhouse, Rean was forced to awaken his power from a long slumber to protect Elise from the Ol-Gadia Magic Knight. Before going anymore berserk, Rean manages to suppress it through the memories of his Class VII friends.
October 30, S1204. When Class VII were outmatched by Scarlet's Spiegel unit, Rean was about to awaken the power as left with no other alternative. But sheathes it after hearing Valimar's voice, and performing his first Awakener's Call.
November 30, S1204. When Ymir was raided by the Northern Jaegers and seeing his parents on the ground, Rean anguishes out the power taking all the jaegers down in anger. Before losing control again, Elise calms his down and learning that his parents were only unconscious.
December 13, S1204. When Rean was shanghaied aboard the Pantagruel and finding Princess Alfin, she referred about everything Elise told her about him and all the things that have happened around him. Realizing that others were him protecting others but thinking the opposite, Rean finally brings peace to himself thus gaining control of his power.
- This portrays Rean as the first Trails character to boost into hyper mode.