Key: SSMatt2
Character: Heero Susanno
Skill(or transformation): 1/16th SSJ
How well do you know the source material?(obviously not relevant if it's a transformation):
Reasoning:  There is plenty of reasoning behind this, not just after seeing Nevari, one of his closest friends go and try to rip Ludi's arm off. There are others trying to stop her, but in the middle of him trying to stop her in his own way, one that might of had him be able to stop her through a non violent way....just maybe.

But that was when Elena stepped in, with all things, to take his life. That sword aimed right at his side, aiming to stab right through him, to have him slowly die while watching Nevari do something terrible. This is traumatising for the King of Braves-especially after being swatted to the side like he was a fly.

With whatever energy and power Elena had from the previous fight too...and it seems that since nothing else works, Elena aims to end Heero right here, despite everything.

What is the moment: The moment is that Heero is in truly dire straights, this was the same person that took out five of them earlier. With Elena having him there, aiming to snuff him out...Heero is having a moment of desperation. This moment comes from the fact he can't do anything, ever. He is the King of Braves, but it never seems to give him enough power to do what he needs to do. While humans are powerful, in this instance, it doesn't seem to be enough...and something will beat and awaken inside him.

That shed of Saiyan heritage, a potential yet to be awakened. One that...despite all of his short comings, will actually push him forwards and allow him to survive....and actually save people.

Save people from themselves, through the way he's always wanted.

With the Oath sworn through Courage.