"It seems it is my turn now." Dexter whispered. He felt like he had to do this, as the other girl, whose potential was unlocked later than his own, was able to transform... As he observed the other people transforming, it just seemed they weren't doing anything particular either to achieve that goal.
At first, Dexter was too nervous to transform: he was standing still, shivering. Then, a lot of things came suddendly into his mind: that Beast, who killed his father, himself finding his father's corpse, then Astros and the contract, and the Beast that Takeshi killed that night...
This started an interesting thought process: Astros needed protection from the Beasts like most people needed protection from criminals; while Astros would give magical powers to people, the normal humans would create the Police Departments: so, like Dexter's father, a cop, would protect others from criminals, Dexter himself would protect others from Beasts... I'm like my father then, I have a duty, and a will to protect someone from a danger. I remember he was very satisfied with his job, so I could do the same... thought the blonde guy, while still standing in the room, with the other people (already transformed) around him.
That sense of duty, those memories, and all of those connections between him and his (late) father... that was what could trigger the transformation!
While he was still "meditating" in the room, Dexter began to feel the weight of something on him, and, most importantly, the energy from within. It was a completely new sensation for him. After a couple seconds that seemed eternal for Dexter, he opened his eyes again and looked at himself.
His clothes were not there anymore; he was wearing some kind of a silver armor instead, with some blue parts. His glasses were still there, and they were the same as before, but he was still seeing everything brighter and clearer. His father's ordinary pistol was still on his right side, as it was before the transformation.
"Well, now it seems I did it." declared Dexter, satisfied with his new achievement.