[His appearance has...shifted. And so has his personality.]

No, walk. Enjoy having a leisurely stroll as the world as we know it gets destroyed.

Idiot.

[This variant of Brainy is apparently not very nice, but he's at least still working on the time travel device.]

Since you're from outside the universe, your past won't be immediately effected, despite your recent past having been spent here. Due to the flexible nature of spacetime in this universe, it'll take time for this timeline to fully collapse.

But once it does, it'll destroy all of you as well, because of all the time you've spent here getting erased.