[The change is usually on more of a gradient, rather than flipping a switch like golden eyes turning on and off, but it's somewhat similar. Things like that develop in very early childhood, you know? When a child experiences trauma so intense or incessant that their brain literally cannot cope with it, they form another vessel to hold the memories for them — or another entity to take the abuse, or comfort them, or punish the offender, or whatever it is that the kid needs and the outside world does not provide — just so they can both get through to the next day.]

Sometimes that entity is half-formed, somewhere between consciousness and subconsciousness, until it's given something to latch onto. An appearance, or a name. As the kid gets older, the tendency to create a collaborative effort in order to get through the stresses of life remain, especially when they're continually put in traumatic situations. And especially when they're handed other entities from a magic butterfly to be friends with, and easily take on those masks as their own face.]

...You know why I did that, Terry? Two reasons.

[Akira's not screaming.]

Number one, you were threatening to kill everybody, and back then I still thought this world was worth saving.

Number two, you were stronger than me, and lording your will over me. That made me want to hurt you.

That's it. Those are the reasons.